[PATCH] x86-64: remove unused variable

Remove unused variable in msr_write().

Reported by D Binderman <dcb314@hotmail.com>.

Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: David Rientjes <rientjes@cs.washington.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Andi Kleen <ak@suse.de>