scripts/yocto-bsp: Fixed typo in parameter that was causing exception

scripts/yocto-bsp: Fixed typo in parameter that was causing exception

There is a typo in the logging parameters, "filname" is being used instead
of "filename". This didn't cause issues before since python 2 didn't
validate unused parameters but with python >= 3.4.3 an exception is
thrown. This patch fixes this parameter name.

[Yocto #9736]

Signed-off-by: Humberto Ibarra <humberto.ibarra.lopez@intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>