wil6210: use GRO

GRO is easy to enable when already using NAPI framework,
and it improves CPU utilisation. Enable it by default.

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Git-commit: b5998e6a3d695c9261a1b1d9cf27db526aa72b3b
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Liron Kuch <lkuch@codeaurora.org>