msm: remote_spinlock: Remove dead code

Remove the following dead functionality:

1. DAL remote spinlocks
	Unused on supported targets and much of the DAL framework no longer
	exists

2. SWP based software locks
	SWP instructions are deprecated on modern ARM architectures

3. Dekkers based software locks
	Dekker's algorithm assumes only two entities will compete for the
	lock.  Supported targets involve more than two entities.

4. Compile-time implementation switching
	Implementation details are determined at runtime via Device Tree

5. Misc unused included headers

Change-Id: I941e508e1688f48a9439d8ce879505ba8f555e34
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>