firmware: arm_scpi: pre-populate dvfs info in scpi_probe

Pre-populating the dvfs info data in scpi_probe allows to make all
memory allocations device-managed. This helps to simplify scpi_remove
and eventually to get rid of scpi_remove completely.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
[sudeep.holla: changed to continue probe even if scpi_dvfs_populate_info fails]
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>