regulator: move the spm-regulator driver to the drivers/regulator directory

Move the spm-regulator driver from the arch/arm/mach-msm
directory into the drivers/regulator directory.  Moving this
driver out of the arch/arm/mach-msm directory allows it to be
shared with architectures other than 'arm'.  In particular,
moving it allows it to be used by arm64.

Also move the header file for the spm-regulator driver from the
arch/arm/mach-msm directory into the include/linux/regulator
directory.  Moving the header file requires updating all files
which include it.

Change-Id: I0c5a20a5f3512ef19c9cdb939342224d11667650
Signed-off-by: David Collins <collinsd@codeaurora.org>