One of the OMAP1 clocks can use the fixed divisor recalculation code
introduced in the OMAP2 clock code, so rename the
omap2_fixed_divisor_recalc() function to omap_fixed_divisor_recalc()
and make it available to all OMAPs.  A followup patch converts the OMAP1
clock.
Signed-off-by: Paul Walmsley <paul@pwsan.com>