firmware_loader: Fix configs for sysfs split

Fix the CONFIGs around register_sysfs_loader(),
unregister_sysfs_loader(), register_firmware_config_sysctl(), and
unregister_firmware_config_sysctl(). The full definitions of the
register_sysfs_loader() and unregister_sysfs_loader() functions should
be used whenever CONFIG_FW_LOADER_SYSFS is defined. The
register_firmware_config_sysctl() and unregister_firmware_config_sysctl()
functions should be stubbed out unless CONFIG_FW_LOADER_USER_HELPER
CONFIG_SYSCTL are both defined.

Signed-off-by: Russ Weight <russell.h.weight@intel.com>
Link: https://lore.kernel.org/r/20220426200356.126085-2-russell.h.weight@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>