camera: vfe32: Init vfe subdev during axi subdev init.

This makes sure vfe subdev is initialized even when
user space doesn't call ioctl to initialize it in RDI
use case.

This is necessary because vfe subdev is used in axi
only case.

Change-Id: I1d8179b28b8cf065b50ae8dabbd14df6cd9a2fef
Signed-off-by: Shuzhen Wang <shuzhenw@codeaurora.org>