firmware: arm_ffa: Add missing rwlock_init() for the driver partition

firmware: arm_ffa: Add missing rwlock_init() for the driver partition

Add the missing rwlock initialization for the FF-A partition associated
the driver in ffa_setup_partitions(). It will the primary scheduler
partition in the host or the VM partition in the virtualised environment.
IOW, it corresponds to the partition with VM ID == drv_info->vm_id.

Fixes: 1b6bf41b7a65 ("firmware: arm_ffa: Add notification handling mechanism")
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20240108-ffa_fixes_6-8-v1-2-75bf7035bc50@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>