[CPUFREQ]: x86, cpufreq: Mark longrun_get_policy with __cpuinit.

This patch fixes the following warning. The function
longrun_cpu_init() is marked with __cpuinit which calls
longrun_get_policy() which is a __init function. So make
longrun_get_policy with __cpuinit.

WARNING: arch/x86/kernel/cpu/cpufreq/longrun.o(.cpuinit.text+0x4c5):
Section mismatch in reference from the function longrun_cpu_init() to
the function .init.text:longrun_get_policy()
The function __cpuinit longrun_cpu_init() references
a function __init longrun_get_policy().
If longrun_get_policy is only used by longrun_cpu_init then
annotate longrun_get_policy with a matching annotation.

Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Signed-off-by: Dave Jones <davej@redhat.com>