OMAP1/2/3 clock: remove paranoid checks in preparation for clock{,2xxx,3xxx}_data.c

Some parts of the clock code took advantage of the fact that the statically
allocated clock tree was in clock{,24xx,34xx}.c's local namespace to do some
extra argument checks.  These are overzealous and are more difficult to
maintain when the clock tree is in a separate namespace, so, remove them.

Signed-off-by: Paul Walmsley <paul@pwsan.com>