firmware: arm_ffa: Fix big-endian support in __ffa_partition_info_get()

firmware: arm_ffa: Fix big-endian support in __ffa_partition_info_get()

Currently the FF-A driver doesn't support big-endian correctly. It is
hard to regularly test the setup due to lack of test infrastructure and
tools.

In order to support full stack, we need to take small steps in getting
the support for big-endian kernel added slowly. This change fixes the
support in __ffa_partition_info_get() so that the response from the
firmware are converted correctly as required. With this change, we can
enumerate all the FF-A devices correctly in the big-endian kernel.

Tested-by: Viresh Kumar <viresh.kumar@linaro.org>
Message-Id: <20250217-ffa_updates-v3-4-bd1d9de615e7@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>