msm: kgsl: Allow mempools to configure from the device tree

Add driver support to configure mempools from the device tree.
This will enable mempools to configure per device specific and
reduces the high kgsl memory usage based on configuration.

CRs-Fixed: 1064046
Change-Id: I0a7e36b7e1fef9d42a4c0fe33d69a4debf15af2f
Signed-off-by: Hareesh Gundu <hareeshg@codeaurora.org>