hwspinlock: Add support to parse spin lock id

The current implementation will use hard coded spin lock id
which will cause conflicts when gvm want to access hardware
spink lock while communicating with remote host over dedicated
smem partition area.

Adding support to parse spin lock id from dt entry. This will
help to configure unique spin lock id for gvm.

Change-Id: I8001c6339a2d823109177dedbfceef9a5bdc2d51
Signed-off-by: Arun Prakash <app@codeaurora.org>