media: venus: venc: Fix default capture format

The default codec after driver open is set to be H264 but the
instance format for capture is wrongly set to H263. Correct this
to H264.

For regular applications this is not a big issue because they set
the format through S_FMT but for example v4l2-compliance does not.

Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>