c0c79461 unintentianally changed the initialization flow of the
decoder: It caused the capture buffers to be initialized on
v4l2_m2m.c:180 in v4l2_configure_contexts(). This breaks h264 decoding
on the Odroid XU4 (RPI4 was not affected).

This commit postpones capture buffer initialization
as before c0c79461 to fix the issue.
Signed-off-by: Andriy Gelman <andriy.gelman@gmail.com>
Signed-off-by: Aman Gupta <aman@tmm1.net>