Staging: sxg: remove firmware files from sgx_ethtool.c

They are not needed here and only cause build warnings and bloat the
object file.

Cc: Mithlesh Thukral <mithlesh@linsyssoft.com>
Cc: LinSysSoft Sahara Team <saharaproj@linsyssoft.com>
Cc: Christopher Harrer <charrer@alacritech.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>