clang static analysis reports this problem

tuner-simple.c:714:13: warning: Assigned value is
  garbage or undefined
        buffer[1] = buffer[3];
                  ^ ~~~~~~~~~
In simple_set_radio_freq buffer[3] used to be done
in-function with a switch of tuner type, now done
by a call to simple_radio_bandswitch which has this case

	case TUNER_TENA_9533_DI:
	case TUNER_YMEC_TVF_5533MF:
		tuner_dbg("This tuner doesn't ...
		return 0;

which does not set buffer[3].  In the old logic, this case
would have returned 0 from simple_set_radio_freq.

Recover this old behavior by returning an error for this
codition. Since the old simple_set_radio_freq behavior
returned a 0, do the same.

Fixes: c7a9f3aa ("V4L/DVB (7129): tuner-simple: move device-specific code into three separate functions")
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>