[Keyboard] Bootmagic does not actually work on BMC boards, removing from panc60 (#5573)

* remove unneeded uart setting

* use pragma once everywhere

* remove custom matrix support

* fixup readme

* set bootmagic to lite

* remove dependency on custom i2c code

* use the right header files and function calls

* remove bootmagic support as it doesn't work on bmc boards

* readme merge artifacts removal

keyboards/panc60/readme.md

@@ -14,7 +14,7 @@ Make example for this keyboard (after setting up your build environment):
 
 Flashing
 
-**Reset Key:** Hold down the key located at `K40`, commonly programmed as left control while plugging in the keyboard. You may also hold down the key located at `K00`, commonly programmed as the `Esc` key. 
+**Reset Key:** Hold down the key located at `K40`, commonly programmed as left control while plugging in the keyboard.
 
 ps2avr(GB) boards use an atmega32a microcontroller and a different bootloader. It is not flashable using the regular QMK methods. 
 

keyboards/panc60/rules.mk

@@ -31,7 +31,7 @@ F_CPU = 12000000
 BOOTLOADER = bootloadHID
 
 # build options
-BOOTMAGIC_ENABLE = lite
+BOOTMAGIC_ENABLE = no
 MOUSEKEY_ENABLE = yes
 EXTRAKEY_ENABLE = yes
 CONSOLE_ENABLE = yes