[media] xc5000: Don't spin waiting for analog lock

The xc5000 driver should not be spinning waiting for an analog lock.
The ioctl() should be returning immediately and the application is
responsible for polling for lock status.

This behavior isn't very visible in cases where you tune to a valid
channel, since lock is usually achieved much faster than 400ms.
However it is highly visible where doing things like changing video
standards, which sends tuning request for a frequency that is
almost never going to have an actual channel on it.

Also fixup the return values to treat zero as success and an actual
error code on error (to be consistent with other functions).  Note
this change has no practical effect at this time as none of the
callers inspect the return value.

Signed-off-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>