media: coda: Simplify H.264 small buffer padding logic

The H.264 small buffer padding is done under
the (ctx->qsequence == 0 && payload < 512) condition.

Given this is the exact same condition immediately
above, we can move it right there, making the code
slightly clearer.

This change shouldn't affect functionality as it's just
cosmetics.

Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>