Add paging_set_default_pat() which sets up the PAT MSR according to util/x86/x86_page_tables.go. Using page attribute types require a matching of the PAT values with the page table entries. This function is just providing the default PAT MSR value to match against the utility. BUG=b:72728953 Change-Id: I7ed34a3565647ffc359ff102d3f6a59fbc93cc22 Signed-off-by: Aaron Durbin <adurbin@chromium.org> Reviewed-on: https://review.coreboot.org/25715 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Furquan Shaikh <furquan@google.com> Reviewed-by: Justin TerAvest <teravest@chromium.org>