msm: gsi: initial commit of GSI driver

This is a snapshot of GSI from kernel msm-4.4 based on
commit 801aa2e38aea ("msm: gsi: enable wake irq")

Change-Id: Id58bce41001aad06d62d94b57d9093e422b84bc1
CRs-Fixed: 1077422
Signed-off-by: Amir Levy <alevy@codeaurora.org>
Signed-off-by: Gidon Studinski <gidons@codeaurora.org>