x86/asm/entry/64: Update path names

The paths mentioned in this file weren't updated through some file
rename commits. Fix them to refer to the correct path.

Signed-off-by: James C Boyd <jcboyd.dev@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: trivial@kernel.org
Link: http://lkml.kernel.org/r/1435781606-3037-1-git-send-email-jcboyd.dev@gmail.com


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