media: hantro: h264: Rename POC_CMP() into HANTRO_CMP()

And use it for all native type comparisons, even if it's not strictly
required. By doing that we make the code more consistent and prevent
from potential incorrect results in case of overflow or when the the
values being compared are both negative.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Tested-by: Francois Buergisser <fbuergisser@chromium.org>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>