sh_eth: check sh_eth_cpu_data::cexcr when dumping registers

When adding the sh_eth_cpu_data::cexcr flag I forgot to add the flag
check to  __sh_eth_get_regs(), causing the non-existing RX packet counter
registers to be considered for dumping on  the R7S72100 SoC (the register
offset sanity check has the final say here)...

Fixes: 4c1d4585 ("sh_eth: add sh_eth_cpu_data::cexcr flag")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Tested-by: Chris Brandt <chris.brandt@renesas.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/renesas/sh_eth.c

@@ -2194,8 +2194,10 @@ static size_t __sh_eth_get_regs(struct net_device *ndev, u32 *buf)
 	add_reg(FRECR);
 	add_reg(TSFRCR);
 	add_reg(TLFRCR);
-	add_reg(CERCR);
-	add_reg(CEECR);
+	if (cd->cexcr) {
+		add_reg(CERCR);
+		add_reg(CEECR);
+	}
 	add_reg(MAFCR);
 	if (cd->rtrate)
 		add_reg(RTRATE);