x86, xsave: Move boot cpu initialization to xsave_init()

This patch moves boot cpu initialization to xsave_init(). Now all cpus
are initialized in one single function.

Signed-off-by: Robert Richter <robert.richter@amd.com>
LKML-Reference: <1279651857-24639-5-git-send-email-robert.richter@amd.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>