Support SPI variant of ST7796

See #499

TFT_Drivers/ST7796_Init.h

@@ -32,14 +32,11 @@
 	writedata(0x01);    //1-dot inversion
 
 	writecommand(0xB6); //Display Function Control
-	writedata(0x20);    //RGB interface for RAM access, RGB transfer in DE mode  
-						          //display data path in memory
-						          //Gate outputs in non-display area in Normal scan 
-						          //Source output in non-display area =V63
-
+	writedata(0x80);    //Bypass
 	writedata(0x02);    //Source Output Scan from S1 to S960, Gate Output scan from G1 to G480, scan cycle=2
 	writedata(0x3B);    //LCD Drive Line=8*(59+1)
 
+
 	writecommand(0xE8); //Display Output Ctrl Adjust
 	writedata(0x40);
 	writedata(0x8A);	
@@ -107,4 +104,4 @@
   begin_tft_write();
 
 	writecommand(0x29); //Display on                                          	
-}
\ No newline at end of file
+}