vmlinux.lds.h: wrap built-in firmware support under FW_LOADER

vmlinux.lds.h: wrap built-in firmware support under FW_LOADER

The firmware loader built-in firmware is only available when FW_LOADER
is built-in, so tuck away the sections for built-in firmware under it.

This ensures no oddball user tries to uses these sections without
first enabling FW_LOADER=y.

Reviewed-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20211021155843.1969401-6-mcgrof@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>