[build] Add MIXERS_MONITOR option to taranis/CMakeLists.txt (but disable for X7).

radio/src/targets/taranis/CMakeLists.txt

@@ -1,6 +1,7 @@
 option(SHUTDOWN_CONFIRMATION "Shutdown confirmation" OFF)
 option(LCD_DUAL_BUFFER "Dual LCD Buffer" OFF)
 option(TARANIS_INTERNAL_PPM "Taranis internal module hack to output PPM" OFF)
+option(MIXERS_MONITOR "Enable Mixers Monitor screen (not available on X7 yet)" OFF)
 
 if(PCB STREQUAL X9E)
   set(STICKS "STANDARD" CACHE STRING "Sticks type (STANDARD/HORUS)")
@@ -137,7 +138,7 @@ if(TARANIS_INTERNAL_PPM)
   add_definitions(-DTARANIS_INTERNAL_PPM)
 endif()
 
-if(MIXERS_MONITOR)
+if(MIXERS_MONITOR AND NOT PCB STREQUAL X7)
   add_definitions(-DMIXERS_MONITOR)
 endif()