config: Update several config files to use board aliases for lcd

Add a sample-lcd.cfg with the defintions for several common "reprap"
style LCD displays that use the EXP1/EXP2 plugs.  Update several
config files to add EXP1/EXP2 board aliases.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

config/sample-lcd.cfg

@@ -0,0 +1,91 @@
+# This file provides example configuration for common "RepRap" style
+# LCD displays that use EXP1/EXP2 plugs.
+#
+# To configure a display from this file, make sure the main
+# printer.cfg file has a [board_pins] config section defining pin
+# aliases for the EXP1/EXP2 plugs, find the appropriate LCD type in
+# this file, and then copy-and-paste that section into printer.cfg.
+#
+# See the "example-extras.cfg" file for description of config parameters.
+
+
+######################################################################
+# "RepRapDiscount 128x64 Full Graphic Smart Controller" type displays
+######################################################################
+
+[display]
+lcd_type: st7920
+cs_pin: EXP1_4
+sclk_pin: EXP1_5
+sid_pin: EXP1_3
+encoder_pins: ^EXP2_3, ^EXP2_5
+click_pin: ^!EXP1_2
+#kill_pin: ^!EXP2_8
+
+[output_pin beeper]
+pin: EXP1_1
+
+
+######################################################################
+# "RepRapDiscount 2004 Smart Controller" type displays
+######################################################################
+
+[display]
+lcd_type: hd44780
+rs_pin: EXP1_4
+e_pin: EXP1_3
+d4_pin: EXP1_5
+d5_pin: EXP1_6
+d6_pin: EXP1_7
+d7_pin: EXP1_8
+encoder_pins: ^EXP2_3, ^EXP2_5
+click_pin: ^!EXP1_2
+#kill_pin: ^!EXP2_8
+
+[output_pin beeper]
+pin: EXP1_1
+
+
+######################################################################
+# 128x64 Full Graphic Creality CR10 / ENDER 3 stockdisplay
+######################################################################
+
+[display]
+lcd_type: st7920
+cs_pin: EXP1_7
+sclk_pin: EXP1_6
+sid_pin: EXP1_8
+encoder_pins: ^EXP1_5, ^EXP1_3
+click_pin: ^!EXP1_2
+
+[output_pin beeper]
+pin: EXP1_1
+
+
+######################################################################
+# MKS Mini 12864 LCD
+######################################################################
+
+# Make sure that the EXP1 and EXP2 are rotated correctly on the
+# display board. The cutouts on the connectors should be towards the
+# center of the PCB. See:
+#   https://reprap.org/wiki/MKS_MINI_12864#Physical_Interface
+# If they are wrong, the connector housing can be pried off carefully
+# with a small screwdriver and relocated the correct way.
+
+[display]
+lcd_type: uc1701
+cs_pin: EXP1_6
+a0_pin: EXP1_7
+contrast: 40
+encoder_pins: ^EXP2_3, ^EXP2_5
+click_pin: ^!EXP1_2
+## Some micro-controller boards may require an spi bus to be specified:
+#spi_bus: spi
+## Alternatively, some micro-controller boards may work with software spi:
+#spi_software_miso_pin: EXP2_1
+#spi_software_mosi_pin: EXP2_6
+#spi_software_sclk_pin: EXP2_2
+
+[output_pin beeper]
+pin: EXP1_1