sh: oprofile: Fix up count size mismatch for common impl.

This reduces the 'count' size in the common support structure to 32-bits
so that it matches up with what oprofile is expecting. The SH7750 code
was using a nasty oprofilefs hack to expose the 48-bit counter, although
no other implementations were. Now that the offending driver has been
killed off, it's possible to restore some semblance of sanity.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>