ST7735: fix RGB/BGR selection issue due to ST7735_XXX vs INITR_XXX confusion

Without this change, color order is always set to RGB,
no matter what ST7735_XXX value is defined in User_Setup.h

TFT_Drivers/ST7735_Defines.h

@@ -107,7 +107,7 @@
 #define TFT_MAD_RGB 0x00
 
 #ifndef TFT_RGB_ORDER
-  #if defined(INITR_BLACKTAB) || defined(INITR_GREENTAB2) || defined(INITB)
+  #if defined(ST7735_BLACKTAB) || defined(ST7735_GREENTAB2) || defined(ST7735_INITB)
     #define TFT_MAD_COLOR_ORDER TFT_MAD_RGB
   #else
     #define TFT_MAD_COLOR_ORDER TFT_MAD_BGR