ARM: mach-shmobile: sh73a0 CPGA fix for PLL CFG bit

PLL1 and PLL2 in the sh73a0 CPGA has a CFG bit that
must be taken into account to correctly calculate the
frequency.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>