microcode: Use request_firmware_direct()

Use the new helper, request_firmware_direct(), for avoiding the
lengthy timeout of non-existing firmware loads.  Especially the Intel
microcode driver suffers from this problem because each CPU triggers
the f/w loading, thus it ends up taking (literally) hours with many
cores.

Tested-by: Prarit Bhargava <prarit@redhat.com>
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>