sds: Make initialization deferring optional

If the clocks needed to access the shared RAM memory are
available when the module is started, there is no need to
defer the initialization of the shared data structures
until a clock is locked.

Change-Id: I70a21d82c721cd13e4b1bdd771f84a5d588a8866
Signed-off-by: Ronald Cron <ronald.cron@arm.com>
Signed-off-by: Chris Kay <chris.kay@arm.com>