Patch merged into coreboot/master: northbridge/intel: add missing #include guards

the following patch was just integrated into master:
commit d7ee9dda708321f80161695714737b0f974509d3
Author: Iru Cai 
Date:   Wed Feb 24 15:03:58 2016 +0800

northbridge/intel: add missing #include guards

I first found the missing of #include guards when I tried to include
    both sandybridge/gma.h and sandybridge/sandybridge.h, but
    sandybridge.h includes gma.h in it and gives a compile error.

Change-Id: I13fdb8014b82e6065be2064137b7ea10062deaca
    Signed-off-by: Iru Cai 
    Reviewed-on: https://review.coreboot.org/13775
    Tested-by: build bot (Jenkins)
    Reviewed-by: Patrick Rudolph

See https://review.coreboot.org/13775 for details.

-gerrit