Fix an invalid kfree in mpfs_sys_controller_delete, by replacing the
devm_kzalloc with a regular kzalloc. Change the error handling in the
probe function to free the sys_controller struct if the probe fails.

> cocci warnings: (new ones prefixed by >>)
> >> drivers/soc/microchip/mpfs-sys-controller.c:73:1-6: WARNING: invalid free of devm_ allocated data
Link: https://lore.kernel.org/linux-mm/202203180259.lgIylRZV-lkp@intel.com/

Fixes: d0054a47 ("soc: add microchip polarfire soc system controller")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Conor Dooley <mail@conchuod.ie>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>