[LIBS] Add the general purpose allocator for special purpose memory (genalloc).

This patch adds the basic general purpose allocator for allocating special
purpose memory (memory that is not managed by the regular malloc/free
interface).
This is used for the port of SRAM allocation driver.
[DRIVERS] Add the generic on-chip SRAM allocation driver support.

This patch allows on-chip SRAM usage with the special purpose generic memory
manager (genalloc).
[ARM] i.MX6Q SRAM device node added in device tree.