[media] vcodec: mediatek: Remove double parentheses

The extra pairs of parentheses are not needed and cause clang
warnings like this:

drivers/media/platform/mtk-vcodec/venc/venc_vp8_if.c:158:32: error: equality comparison with extraneous parentheses [-Werror,-Wparentheses-equality]
                if ((inst->work_bufs[i].size == 0))
                     ~~~~~~~~~~~~~~~~~~~~~~~~^~~~
drivers/media/platform/mtk-vcodec/venc/venc_vp8_if.c:158:32: note: remove extraneous parentheses around the comparison to silence this warning
                if ((inst->work_bufs[i].size == 0))
                    ~                        ^   ~
drivers/media/platform/mtk-vcodec/venc/venc_vp8_if.c:158:32: note: use '=' to turn this equality comparison into an assignment
                if ((inst->work_bufs[i].size == 0))
                                             ^~
                                             =

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>