msm: vidc: Addition of VIDIOC_QUERY_EXT_CTRL ioctl

Adding vidc support for VIDIOC_QUERY_EXT_CTRL ioctl. This ioctl will
return the details for the V4L2 control identified by the ID provided
by the user or the next supported control based upon the flags
provided by the user.

Change-Id: I68161ceb000a46a8e54333ab39c0229f8fbdbf72
Signed-off-by: Akshay Chandrashekhar Kalghatgi <akalghat@codeaurora.org>