media: dvb-frontends: tda10048: Make the range of z explicit.

media: dvb-frontends: tda10048: Make the range of z explicit.

The datasheet recommends 55MHz frequency sampling, with a max of 69 MHz.
(Kudos to Kosta Stefanov for the calculations).

Replace z with a 32 bit uint, and make the range of the variable
explicit.

Found by cocci:
drivers/media/dvb-frontends/tda10048.c:345:1-7: WARNING: do_div() does a 64-by-32 division, please consider using div64_u64 instead.

Reviewed-by: Kosta Stefanov <costa.stephanoff@gmail.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>