v4l2: fix the memory leak

commit 9985432a82e6700cf9759f413ecaecbf617318cb

check for fh->dev being NULL before kzalloc to fix the memory leak

Change-Id: I3377ef39297f63c692aa5451d2bdbe327e2df18a
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>