ARM: mach-shmobile: fix sh7372 after a recent clock framework rework

The updated sh clock framework has introduced a .nr_freqs element of struct
clk, which has to be initialised with the number of possible frequencies.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>