stmmac: use one memset() to reset TDES01

Use one memset() to reset all TDES01 fields instead
of one by one to reduce number of instructions.
Signed-off-by: NGiuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/stmmac/enh_desc.c

@@ -284,7 +284,7 @@ static void enh_desc_release_tx_desc(struct dma_desc *p)
 {
 	int ter = p->des01.etx.end_ring;
 
-	memset(p, 0, sizeof(struct dma_desc));
+	memset(p, 0, offsetof(struct dma_desc, des2));
 	p->des01.etx.end_ring = ter;
 }
 

drivers/net/stmmac/norm_desc.c

@@ -174,22 +174,7 @@ static void ndesc_release_tx_desc(struct dma_desc *p)
 {
 	int ter = p->des01.tx.end_ring;
 
-	/* clean field used within the xmit */
-	p->des01.tx.first_segment = 0;
-	p->des01.tx.last_segment = 0;
-	p->des01.tx.buffer1_size = 0;
-
-	/* clean status reported */
-	p->des01.tx.error_summary = 0;
-	p->des01.tx.underflow_error = 0;
-	p->des01.tx.no_carrier = 0;
-	p->des01.tx.loss_carrier = 0;
-	p->des01.tx.excessive_deferral = 0;
-	p->des01.tx.excessive_collisions = 0;
-	p->des01.tx.late_collision = 0;
-	p->des01.tx.heartbeat_fail = 0;
-	p->des01.tx.deferred = 0;
-
+	memset(p, 0, offsetof(struct dma_desc, des2));
 	/* set termination field */
 	p->des01.tx.end_ring = ter;
 }