dt-bindings: nvmem: Add DT bindings for QTI SDAM driver

QTI SDAM driver allows PMIC peripherals to access the shared
memory that is available on QTI PMICs. Add device tree bindings
for it.

This snapshot is taken as of msm-4.14
commit 9bb584ae3a9d ("msm/sde/rotator: Add rev checks for sdmmagpie").

Change-Id: Ia8ce10171f9cfa5249dc69c7edb4d66cb959ca80
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>