soc: microchip: mpfs-mss-top-sysreg: Fix resource leak on driver unbind

soc: microchip: mpfs-mss-top-sysreg: Fix resource leak on driver unbind

[ Upstream commit 3bfc213d4675736567a4e263c51c25144d565949 ]

Use devm_mfd_add_devices() instead of mfd_add_devices() to ensure
child devices are properly removed when the driver unbinds.

Fixes: 4aac11c9a6e7 ("soc: microchip: add mfd drivers for two syscon regions on PolarFire SoC")
Signed-off-by: Felix Gu <ustc.gu@gmail.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>