x86, mce, severity: Clean up trivial coding style problems

More specifically:

- sort bits in the macros
- use BITCLR/BITSET
- coordinate message pattern
- use m for struct mce
- cleanup for severities_debugfs_init()

No functional change.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/4DEED679.9090503@jp.fujitsu.com


Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>