[PATCH] cpufreq-nforce2.c fix u32<0 test

Thanks to LinuxICC (http://linuxicc.sf.net), a comparison of a u32 less
than 0 was found, this patch changes the variable to a signed int so that
comparison is meaningful.

Signed-off-by: Gabriel A. Devenyi <ace@staticwave.ca>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Dave Jones <davej@redhat.com>