sh_eth: add/use RMCR.RNC bit

Declare 'enum RMCR_BIT' containing the single member for the RMCR.RNC bit and
replace bare numbers in the driver by  this mnemonic.

Suggested-by: David Miller <davem@davemloft.net>
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/renesas/sh_eth.c

@@ -483,7 +483,7 @@ static struct sh_eth_cpu_data sh7757_data = {
 	.register_type	= SH_ETH_REG_FAST_SH4,
 
 	.eesipr_value	= DMAC_M_RFRMER | DMAC_M_ECI | 0x003fffff,
-	.rmcr_value	= 0x00000001,
+	.rmcr_value	= RMCR_RNC,
 
 	.tx_check	= EESR_FTC | EESR_CND | EESR_DLC | EESR_CD | EESR_RTO,
 	.eesr_err_check	= EESR_TWB | EESR_TABT | EESR_RABT | EESR_RFE |
@@ -561,7 +561,7 @@ static struct sh_eth_cpu_data sh7757_data_giga = {
 			  EESR_RFE | EESR_RDE | EESR_RFRMER | EESR_TFE |
 			  EESR_TDE | EESR_ECI,
 	.fdr_value	= 0x0000072f,
-	.rmcr_value	= 0x00000001,
+	.rmcr_value	= RMCR_RNC,
 
 	.irq_flags	= IRQF_SHARED,
 	.apr		= 1,
@@ -689,7 +689,7 @@ static struct sh_eth_cpu_data r8a7740_data = {
 			  EESR_RFE | EESR_RDE | EESR_RFRMER | EESR_TFE |
 			  EESR_TDE | EESR_ECI,
 	.fdr_value	= 0x0000070f,
-	.rmcr_value	= 0x00000001,
+	.rmcr_value	= RMCR_RNC,
 
 	.apr		= 1,
 	.mpr		= 1,