[CPUFREQ] speedstep-ich SMT support.

[CPUFREQ] speedstep-ich SMT support.
i have noticed that the most recent vanilla kernel oopses on a P4M-HT
(because only one CPU is registered in sysfs but 2 are informed of a
change of state). also there are some returns out of subroutines before
set_cpus_allowed() is performed to restore the mask prior to entering
the subroutine (this should not matter on uniprocessor systems, but
still...).

this patch should fix these 2 issues. for the first one, it registers
all logical cpu's and a tiny modification is made in cpufreq.c to
perform a policy change on all siblings.

From: Christian Hoelbling
Signed-off-by: Dave Jones <davej@redhat.com>