media: qcom: don't go past the array

As reported by smatch:

	drivers/media/platform/qcom/camss-8x16/camss-vfe.c:1136 vfe_release_wm() error: buffer overflow 'vfe->wm_output_map' 7 <= 7

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>