firmware: arm_ffa: Remove incorrect assignment of driver_data

The ffa core driver currently assigns its own driver information
to individual ffa device driver_data which is wrong. Firstly, it leaks
this core driver information to individual ffa_device and hence to
ffa_driver. Secondly the ffa_device driver_data is for use by individual
ffa_driver and not for this core driver managing all those devices.

Link: https://lore.kernel.org/r/20220429113946.2087145-2-sudeep.holla@arm.com


Fixes: d0c0bce8 ("firmware: arm_ffa: Setup in-kernel users of FFA partitions")
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>