drm/sun4i: fix HSYNC and VSYNC polarity

Differently from other Lcd signals, HSYNC and VSYNC signals
result inverted if their bits are cleared to 0.

Invert their settings of IO_POL register.
Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1518717288-123578-1-git-send-email-giulio.benetti@micronovasrl.com

drivers/gpu/drm/sun4i/sun4i_tcon.c

@@ -394,10 +394,10 @@ static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon,
 		     SUN4I_TCON0_BASIC3_H_SYNC(hsync));
 
 	/* Setup the polarity of the various signals */
-	if (!(mode->flags & DRM_MODE_FLAG_PHSYNC))
+	if (mode->flags & DRM_MODE_FLAG_PHSYNC)
 		val |= SUN4I_TCON0_IO_POL_HSYNC_POSITIVE;
 
-	if (!(mode->flags & DRM_MODE_FLAG_PVSYNC))
+	if (mode->flags & DRM_MODE_FLAG_PVSYNC)
 		val |= SUN4I_TCON0_IO_POL_VSYNC_POSITIVE;
 
 	regmap_update_bits(tcon->regs, SUN4I_TCON0_IO_POL_REG,