Add SSE3 dependent code

Add SSE3 dependent code

This change separates out changes that were initially found
in the commit for XHCI and AHCI changes to "arch/x86/Makefile.
inc".  It also corrects a comment.  The SSE3 dependent code
adds a pair of CR4 access functions and a blob of code that
re-sets CR4.OSFXSR and CR4.OSXMMEXCPT.

Change-Id: Id97256978da81589d97dcae97981a049101b5258
Signed-off-by: Frank Vibrans <frank.vibrans@amd.com>
Signed-off-by: efdesign98 <efdesign98@gmail.com>
Reviewed-on: http://review.coreboot.org/113
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>