x86/mce: Rename mce_log()'s argument

We call it everywhere "struct mce *m". Adjust that here too to avoid
confusion.

No functionality change.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/20170327093304.10683-3-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>