fix: disable RTC_BACKUP_RAM for MT12 (#6223)

radio/src/targets/taranis/CMakeLists.txt

@@ -542,7 +542,6 @@ elseif ((CPU_TYPE_FULL STREQUAL STM32F407xE) OR (CPU_TYPE_FULL STREQUAL STM32F40
   if (CPU_TYPE_FULL STREQUAL STM32F407xG)
     set(TARGET_FLASH_SIZE 1M)
     add_definitions(-DSTM32F407xG)
-    set(RTC_BACKUP_RAM YES)
   else()
     set(USBJ_EX OFF)
   endif()
@@ -555,6 +554,10 @@ else()
   message(FATAL_ERROR "Unknown CPU_TYPE_FULL" )
 endif()
 
+if ((CPU_TYPE_FULL STREQUAL STM32F407xG) AND (NOT PCBREV STREQUAL MT12))
+  set(RTC_BACKUP_RAM YES)
+endif()
+
 if(FUNCTION_SWITCHES)
   add_definitions(-DFUNCTION_SWITCHES)
 endif()