firmware: microchip: Fix over-requested allocation size

firmware: microchip: Fix over-requested allocation size

cocci warnings: (new ones prefixed by >>)
>> drivers/firmware/microchip/mpfs-auto-update.c:387:72-78:
   ERROR: application of sizeof to pointer
   drivers/firmware/microchip/mpfs-auto-update.c:170:72-78:
   ERROR: application of sizeof to pointer

response_msg is a pointer to u32, so the size of element it points to is
supposed to be a multiple of sizeof(u32), rather than sizeof(u32 *).

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202403040516.CYxoWTXw-lkp@intel.com/
Signed-off-by: Dawei Li <dawei.li@shingroup.cn>
Fixes: ec5b0f1193ad ("firmware: microchip: add PolarFire SoC Auto Update support")
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>