The firmware_fallback_sysfs had some changes at their
parameters. Those ended by dropping a documentation for
such parameter. Re-add it.

Fixes: 89287c16 ("firmware: Store opt_flags in fw_priv")
Fixes: c2c07616 ("firmware_loader: change enum fw_opt to u32")
Signed-off-by: NMauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/23ec441bb9c206f5899b5d64d34e5c9f6add5fd9.1601990386.git.mchehab+huawei@kernel.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>