locking/mcs: Allow architecture specific asm files to be used for contended case

This patch allows each architecture to add its specific assembly optimized
arch_mcs_spin_lock_contended and arch_mcs_spinlock_uncontended for
MCS lock and unlock functions.

Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: AswinChandramouleeswaran <aswin@hp.com>
Cc: George Spelvin <linux@horizon.com>
Cc: Rik vanRiel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: MichelLespinasse <walken@google.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Alex Shi <alex.shi@linaro.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Figo.zhang" <figo1802@gmail.com>
Cc: "Paul E.McKenney" <paulmck@linux.vnet.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Waiman Long <waiman.long@hp.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew R Wilcox <matthew.r.wilcox@intel.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1390347382.3138.67.camel@schen9-DESK
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Git-commit: ddf1d169c0a489d498c1799a7043904a43b0c159
[joonwoop@codeaurora.org: Resolve merge conflicts; we don't have changes
for arch other than ARM/ARM64]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>

Conflicts:
	arch/alpha/include/asm/Kbuild
	arch/arc/include/asm/Kbuild
	arch/arm64/include/asm/Kbuild
	arch/avr32/include/asm/Kbuild
	arch/blackfin/include/asm/Kbuild
	arch/cris/include/asm/Kbuild
	arch/frv/include/asm/Kbuild
	arch/hexagon/include/asm/Kbuild
	arch/ia64/include/asm/Kbuild
	arch/m32r/include/asm/Kbuild
	arch/m68k/include/asm/Kbuild
	arch/metag/include/asm/Kbuild
	arch/microblaze/include/asm/Kbuild
	arch/mips/include/asm/Kbuild
	arch/mn10300/include/asm/Kbuild
	arch/parisc/include/asm/Kbuild
	arch/powerpc/include/asm/Kbuild
	arch/s390/include/asm/Kbuild
	arch/score/include/asm/Kbuild
	arch/sh/include/asm/Kbuild
	arch/sparc/include/asm/Kbuild
	arch/tile/include/asm/Kbuild
	arch/um/include/asm/Kbuild
	arch/x86/include/asm/Kbuild
	arch/xtensa/include/asm/Kbuild