fm10k: prevent possibly uninitialized variable

If 'attr_flag < (1 << (2 * FM10K_TEST_MSG_NESTED))' is ever false, err
will be used uninitialized.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_ethtool.c b/drivers/net/ethernet/intel/fm10k/fm10k_ethtool.c
index c67121c..2e4ea88 100644
--- a/drivers/net/ethernet/intel/fm10k/fm10k_ethtool.c
+++ b/drivers/net/ethernet/intel/fm10k/fm10k_ethtool.c
@@ -937,7 +937,7 @@
 	struct fm10k_mbx_info *mbx = &hw->mbx;
 	u32 attr_flag, test_msg[6];
 	unsigned long timeout;
-	int err;
+	int err = -EINVAL;
 
 	/* For now this is a VF only feature */
 	if (hw->mac.type != fm10k_mac_vf)