media: VPU: mediatek: don't pass an unused parameter

The load_requested_vpu() function returns a freed vpu_fw pointer.  It's
not used so it doesn't cause any problems, but Smatch complains about
it:

    drivers/media/platform/mtk-vpu/mtk_vpu.c:578 vpu_load_firmware()
    warn: passing freed memory 'vpu_fw'

We can clean up the code a bit and silence the static checker warning
by not passing the parameter at all.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>