x86 msr driver: Misc cpuinit annotations

msr_class_cpu_callback() can be marked __cpuinit, being the notifier callback
for a __cpuinitdata notifier_block.  So can be marked msr_device_create() too,
called only from the newly-__cpuinit msr_class_cpu_callback() or from
__init-marked msr_init().

Signed-off-by: Satyam Sharma <satyam@infradead.org>
Cc: Andi Kleen <ak@suse.de>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>