msm: samarium: Enable low power mode drivers at boot

Low Power Mode drivers need to be initialized before many other platform
devices. Initialize these drivers in board file.
Allow the architecture to compile and include low power mode drivers in
Kconfig.

Change-Id: I223c28b37ba056ea1b2568cd23425139914a2e5e
Signed-off-by: Archana Sathyakumar <asathyak@codeaurora.org>