ice: ignore protocol field in GTP offload

Commit 34a89775 ("ice: Add support for inner etype in switchdev")
added the ability to match on inner ethertype. A side effect of that change
is that it is now impossible to add some filters for protocols which do not
contain inner ethtype field. tc requires the protocol field to be specified
when providing certain other options, e.g. src_ip. This is a problem in
case of GTP - when user wants to specify e.g. src_ip, they also need to
specify protocol in tc command (otherwise tc fails with: Illegal "src_ip").
Because GTP is a tunnel, the protocol field is treated as inner protocol.
GTP does not contain inner ethtype field and the filter cannot be added.

To fix this, ignore the ethertype field in case of GTP filters.

Fixes: 9a225f81 ("ice: Support GTP-U and GTP-C offload in switchdev")
Signed-off-by: Marcin Szycik <marcin.szycik@linux.intel.com>
Tested-by: Sandeep Penigalapati <sandeep.penigalapati@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>