Add support to parse sram base and size from dt

In direct drive configuration, linux kernel driver needs to probe SRAM
and provide base address to the NPU. This patch adds support to parse
the base address and size of SRAM and store it in the device instance.

Signed-off-by: Rajasekaran Kalidoss <rajasekaran.kalidoss@arm.com>
Change-Id: If5a64a9b0e1e75dc5d168d761230f13b3f400d44