arm: allwinner: clk: Add printfs when we cannot set the correct freq

For some unknown reason this seems to fix this function when we printf
the best variable. This isn't a delay problem as doing a printf without
it doesn't solve this problem.
This is way above my pay grade so add some printf that shouldn't be printed
in 99% of the case anyway.
Fix booting on most Allwinner boards as the mmc IP uses a NM clock.

Reported by: Alexander Mishin <mishin@mh.net.ru>
MFC after: 3 days
X-MFC-With: 363887