watchdog: sp5100_tco: Fix a memory leak of EFCH MMIO resource

Unlike release_mem_region(), a call to release_resource() does not
free the resource, so it has to be freed explicitly to avoid a memory
leak.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Fixes: 0578fff4 ("Watchdog: sp5100_tco: Add initialization using EFCH MMIO")
Cc: Terry Bowman <terry.bowman@amd.com>
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220621152840.420a0f4c@endymion.delvare


Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>