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/db-xc3-24g4xg_defconfig b/configs/db-xc3-24g4xg_defconfig
index aa47b84..dd087ff 100644
--- a/configs/db-xc3-24g4xg_defconfig
+++ b/configs/db-xc3-24g4xg_defconfig
@@ -40,6 +40,7 @@
 CONFIG_ENV_IS_IN_SPI_FLASH=y
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_ARP_TIMEOUT=200
+CONFIG_NET_RETRY_COUNT=50
 CONFIG_DM_I2C=y
 CONFIG_SYS_I2C_MVTWSI=y
 # CONFIG_MMC is not set