[media] m920x: Fix uninitialized variable warning

drivers/media/usb/dvb-usb/m920x.c:91:6: warning: "ret" may be used uninitialized in this function [-Wuninitialized]
drivers/media/usb/dvb-usb/m920x.c:70:6: note: "ret" was declared here
This is real, if a remote control has an empty initialization sequence
we would get success or failure randomly.
OTOH the initialization of ret in m920x_init is needless, the function
returns with an error as soon as an error happens, so the last return
can only be a success and we can hard-code 0 there.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>