Properly clear IRQ status in order to fix "Spurious IRQ" message from AINT.

This register is not documented in TRM but that's what linux driver does

sys/arm/ti/am335x/am335x_lcd.c

@@ -150,6 +150,7 @@ __FBSDID("$FreeBSD$");
 #define		IRQ_SYNC_LOST		(1 << 2)
 #define		IRQ_RASTER_DONE		(1 << 1)
 #define		IRQ_FRAME_DONE		(1 << 0)
+#define	LCD_END_OF_INT_IND	0x68
 #define	LCD_CLKC_ENABLE		0x6C
 #define		CLKC_ENABLE_DMA		(1 << 2)
 #define		CLKC_ENABLE_LDID	(1 << 1)
@@ -397,6 +398,8 @@ am335x_lcd_intr(void *arg)
 	if (reg & IRQ_ACB) {
 		/* TODO: Handle ACB */
 	}
+
+	LCD_WRITE4(sc, LCD_END_OF_INT_IND, 0);
 }
 
 static int