msm: smem: remove MSM_SHARED_RAM_BASE dependence

MSM_SHARED_RAM_BASE is used to read the static fields of smem region
like version info, heap info and table of content.

For targets based on device tree, the MSM_SHARED_RAM_BASE may not be
necessary. so remove the dependence by using smem_get_version() and
smem_find() APIs.

Change-Id: I17064b4c928b5de7266c742b2c8d588b0859a29f
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>