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/crs305-1g-4s-bit_defconfig b/configs/crs305-1g-4s-bit_defconfig
index 530ee83..a5f0a21 100644
--- a/configs/crs305-1g-4s-bit_defconfig
+++ b/configs/crs305-1g-4s-bit_defconfig
@@ -33,6 +33,7 @@
 CONFIG_ENV_IS_IN_SPI_FLASH=y
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_ARP_TIMEOUT=200
+CONFIG_NET_RETRY_COUNT=50
 CONFIG_BLK=y
 CONFIG_BOOTCOUNT_LIMIT=y
 CONFIG_BOOTCOUNT_ENV=y