media: mtk-vcodec: mtk_vcodec_dec.c: fix comparison to bool

Fix the following coccinelle reports:

drivers/media/platform/mtk-vcodec/mtk_vcodec_dec.c:197:14-35:
WARNING: Comparison to bool

drivers/media/platform/mtk-vcodec/mtk_vcodec_dec.c:198:7-29:
WARNING: Comparison to bool

drivers/media/platform/mtk-vcodec/mtk_vcodec_dec.c:451:12-19:
WARNING: Comparison to bool

drivers/media/platform/mtk-vcodec/mtk_vcodec_dec.c:1159:6-15:
WARNING: Comparison to bool

By replacing (cond == true) with (cond) and (cond == false) with
(!cond)

Found using - Coccinelle (http://coccinelle.lip6.fr

)

Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>