firmware: arm_ffa: Upgrade FF-A version to v1.2 in the driver

The basic and mandatory features of FF-A v1.2 are all supported now.
The driver supported version can be bumped from v1.1 to v1.2

Tested-by: Viresh Kumar <viresh.kumar@linaro.org>
Message-Id: <20250217-ffa_updates-v3-11-bd1d9de615e7@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>