parselogs.py: Whitelist iwlwifi firmware load error messages

parselogs.py: Whitelist iwlwifi firmware load error messages

The iwlwifi module of any given kernel has a minimum and maximum
supported firmware version. The kernel begins by attempting to load the
maximum version, and decrements until it is successful. The 4.8 kernel's
maximum supported firmware version is 24, but thus far only 22 has been
released, meaning we get errors for 24 and 23.

Filter out iwlwifi firmware load error messages, as they are not
necessarily indicative of real problems.

(From OE-Core rev: 7df570c2310efac8f9898da15deaac2b7df16655)

Signed-off-by: California Sullivan <california.l.sullivan@intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>