libertas: register sysfs groups properly

The libertas driver was trying to register sysfs groups "by hand" which
causes them to be created _after_ the device is initialized and
announced to userspace, which causes races and can prevent userspace
tools from seeing the sysfs files correctly.

Fix this up by using the built-in sysfs_groups pointers in struct
net_device which were created for this very reason, fixing the race
condition, and properly allowing for any error that might have occured
to be handled properly.

Cc: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210503115736.2104747-54-gregkh@linuxfoundation.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>