soc: qcom: add OCMEM driver

The OCMEM driver handles allocation and configuration of the On Chip
MEMory that is present on some Snapdragon SoCs. Devices which have
OCMEM do not have GMEM inside the GPU core, so the GPU must instead
use OCMEM to be functional. Since the GPU is currently the only OCMEM
user with an upstream driver, this is just a minimal implementation
sufficient for statically allocating to the GPU it's chunk of OCMEM.

This driver currently does not read the gmu-sram node that is described
in the device tree bindings. The starting memory address of the GPU's
reserved memory region is hardcoded to zero to match what the hardware
expects. The driver can be updated to read the reserved memory regions
from device tree once other users of OCMEM are added upstream.

Signed-off-by: Brian Masney <masneyb@onstation.org>
Co-developed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Tested-by: Gabriel Francisco <frc.gabrielgmail.com>
Signed-off-by: Rob Clark <robdclark@chromium.org>