iwlwifi: remove legacy isr tasklet

After driver split, no need for support legacy isr, remove it.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-lib.c b/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
index 2003c1d..8163a0e 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
@@ -652,8 +652,7 @@
 	const u32 rfdnlog = RX_QUEUE_SIZE_LOG; /* 256 RBDs */
 	u32 rb_timeout = 0; /* FIXME: RX_RB_TIMEOUT for all devices? */
 
-	if (!priv->cfg->base_params->use_isr_legacy)
-		rb_timeout = RX_RB_TIMEOUT;
+	rb_timeout = RX_RB_TIMEOUT;
 
 	if (priv->cfg->mod_params->amsdu_size_8K)
 		rb_size = FH_RCSR_RX_CONFIG_REG_VAL_RB_SIZE_8K;