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/meesc_defconfig b/configs/meesc_defconfig
index e9f7288..9e5eb5a 100644
--- a/configs/meesc_defconfig
+++ b/configs/meesc_defconfig
@@ -29,6 +29,7 @@
 CONFIG_OF_CONTROL=y
 CONFIG_ENV_IS_IN_NAND=y
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
+CONFIG_NET_RETRY_COUNT=20
 CONFIG_DM=y
 CONFIG_CLK=y
 CONFIG_CLK_AT91=y