Apply PIO-supported custom_option for deps (#18935)

buildroot/share/PlatformIO/scripts/common-dependencies.py

 			FEATURE_CONFIG[feature] = { 'lib_deps': [] }
 		add_to_feat_cnf(feature, key[1])
 
-	# Add options matching marlin.MY_OPTION to the pile
+	# Add options matching custom_marlin.MY_OPTION to the pile
 	all_opts = env.GetProjectOptions()
 	for n in all_opts:
-		mat = re.match(r'marlin\.(.+)', n[0])
+		mat = re.match(r'custom_marlin\.(.+)', n[0])
 		if mat:
 			try:
 				val = env.GetProjectOption(n[0])

platformio.ini

 lib_deps       = ${common.lib_deps}
   SoftwareSerialM
   Adafruit SPIFlash
-marlin.SDSUPPORT = SdFat - Adafruit Fork
+custom_marlin.SDSUPPORT = SdFat - Adafruit Fork
 debug_tool     = jlink
 
 #################################
 src_filter        = ${common.default_src_filter} +<src/HAL/LPC1768>
 lib_deps          = ${common.lib_deps}
   Servo
-marlin.USES_LIQUIDCRYSTAL = LiquidCrystal@1.0.0
-marlin.NEOPIXEL_LED = Adafruit NeoPixel=https://github.com/p3p/Adafruit_NeoPixel/archive/1.5.0.zip
+custom_marlin.USES_LIQUIDCRYSTAL = LiquidCrystal@1.0.0
+custom_marlin.NEOPIXEL_LED = Adafruit NeoPixel=https://github.com/p3p/Adafruit_NeoPixel/archive/1.5.0.zip
 build_flags       = ${common.build_flags} -DU8G_HAL_LINKS -IMarlin/src/HAL/LPC1768/include -IMarlin/src/HAL/LPC1768/u8g
   # debug options for backtrace
   #-funwind-tables
 lib_deps          = ${common.lib_deps}
   SoftwareSerialM
   USBComposite for STM32F1@0.91
-marlin.NEOPIXEL_LED = Adafruit NeoPixel=https://github.com/ccccmagicboy/Adafruit_NeoPixel#meeb_3dp_use
+custom_marlin.NEOPIXEL_LED = Adafruit NeoPixel=https://github.com/ccccmagicboy/Adafruit_NeoPixel#meeb_3dp_use
 debug_tool        = stlink
 upload_protocol   = dfu