commit a44323e2 upstream.

The current code goes through a lot of indirection just to call a
known handler.  Simplify it: just call the handlers directly.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
[bwh: Backported to 3.16: old code forwarded to uvc_v4l2_ioctl()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>