i40e: Fix incorrect use of tx_itr_setting when checking for Rx ITR setup

It looks like there was either a copy/paste error or just a typo that
resulted in the Tx ITR setting being used to determine if we were using
adaptive Rx interrupt moderation or not.

This patch fixes the typo.

Fixes: 65e87c0398f5 ("i40evf: support queue-specific settings for interrupt moderation")
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e_txrx.c

@@ -2269,7 +2269,7 @@ static inline void i40e_update_enable_itr(struct i40e_vsi *vsi,
 		goto enable_int;
 	}
 
-	if (ITR_IS_DYNAMIC(tx_itr_setting)) {
+	if (ITR_IS_DYNAMIC(rx_itr_setting)) {
 		rx = i40e_set_new_dynamic_itr(&q_vector->rx);
 		rxval = i40e_buildreg_itr(I40E_RX_ITR, q_vector->rx.itr);
 	}