locking/csd_lock: Explicitly inline csd_lock*() helpers

While the compiler tends to already to it for us (except for
csd_unlock), make it explicit. These helpers mainly deal with
the ->flags, are short-lived  and can be called, for example,
from smp_call_function_many().

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@stgolabs.net
Link: http://lkml.kernel.org/r/1457574936-19065-2-git-send-email-dbueso@suse.de


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