media: vsp1: tidyup VI6_HGT_LBn_H() macro

The address of VSP2_VI6_HGT_LBx_H are
	VSP2_VI6_HGT_LB0_H : 0x3428
	VSP2_VI6_HGT_LB1_H : 0x3430
	VSP2_VI6_HGT_LB2_H : 0x3438
	VSP2_VI6_HGT_LB3_H : 0x3440

Thus, VI6_HGT_LBn_H() macro should start from 0x3420 instead of 0x3430.
This patch fixes it.

Fixes: 26e0ca22 ("[media] v4l: Renesas R-Car VSP1 driver")

Reported-by: Koji Matsuoka <koji.matsuoka.xm@renesas.com>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>