firmware: arm_ffa: Add missing rwlock_init() in ffa_setup_partitions()

Add the missing rwlock initialization for the individual FF-A partition
information in ffa_setup_partitions().

Fixes: 0184450b

 ("firmware: arm_ffa: Add schedule receiver callback mechanism")
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20240108-ffa_fixes_6-8-v1-1-75bf7035bc50@arm.com


Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>