drivers: base: firmware_loader: add proper SPDX identifiers on files that did not have them.

There were two files in the firmware_loader code that did not have SPDX
identifiers on them, so fix that up.

Cc: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/firmware_loader/Kconfig

+# SPDX-License-Identifier: GPL-2.0
 menu "Firmware loader"
 
 config FW_LOADER

drivers/base/firmware_loader/builtin/.gitignore

+# SPDX-License-Identifier: GPL-2.0
 *.gen.S