Convert CONFIG_NET_RETRY_COUNT to Kconfig

This converts the following to Kconfig:
   CONFIG_NET_RETRY_COUNT

Cc: Ramon Fried <rfried.dev@gmail.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/controlcenterdc_defconfig b/configs/controlcenterdc_defconfig
index da8ed9a..abbb5cc 100644
--- a/configs/controlcenterdc_defconfig
+++ b/configs/controlcenterdc_defconfig
@@ -60,6 +60,7 @@
 CONFIG_USE_BOOTFILE=y
 CONFIG_BOOTFILE="ccdc.img"
 CONFIG_ARP_TIMEOUT=200
+CONFIG_NET_RETRY_COUNT=50
 CONFIG_SPL_OF_TRANSLATE=y
 CONFIG_SCSI_AHCI=y
 CONFIG_DM_PCA953X=y