media: venus: vdec: Fix non reliable setting of LAST flag

In real use of dynamic-resolution-change it is observed that the
LAST buffer flag (which marks the last decoded buffer with the
resolution before the resolution-change event) is not reliably set.

Fix this by set the LAST buffer flag on next queued capture buffer
after the resolution-change event.

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