x86, fpu: Merge fpu_init()

Make fpu_init() handle 32-bit setup.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <1283563039-3466-3-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>