igb: Fix passing 0 to ERR_PTR in igb_run_xdp()

igb: Fix passing 0 to ERR_PTR in igb_run_xdp()

igb_run_xdp() converts customed xdp action to a negative error code
with the sk_buff pointer type which be checked with IS_ERR in
igb_clean_rx_irq(). Remove this error pointer handing instead use plain
int return value.

Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Chandan Kumar Rout <chandanx.rout@intel.com> (A Contingent Worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Link: https://patch.msgid.link/20250106221929.956999-10-anthony.l.nguyen@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>