x86/Documentation: Fix various typos in Documentation/x86/ files

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: corbet@lwn.net
Cc: linux-doc@vger.kernel.org
Link: http://lkml.kernel.org/r/20160701034601.30308-1-standby24x7@gmail.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>