include: configs: ls1028a: set SYS_RX_ETH_BUFFER to 8

LS1028A ethernet interfaces work with at least 8 BDs, set number of buffers
to match that.
Signed-off-by: NAlex Marginean <alexm.osslist@gmail.com>
Reviewed-by: NBin Meng <bmeng.cn@gmail.com>
Acked-by: NJoe Hershberger <joe.hershberger@ni.com>

include/configs/ls1028a_common.h

@@ -194,4 +194,8 @@
 #include <asm/fsl_secure_boot.h>
 #endif
 
+/* Ethernet */
+/* smallest ENETC BD ring has 8 entries */
+#define CONFIG_SYS_RX_ETH_BUFFER		8
+
 #endif /* __L1028A_COMMON_H */