V4L/DVB (8843): tda10048_firmware_upload(): fix a memory leak

This patch fixes a memory leak ("fw" wasn't freed).

Reported-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>