Convert CONFIG_ARP_TIMEOUT to Kconfig

This converts the following to Kconfig:
   CONFIG_ARP_TIMEOUT

Cc: Ramon Fried <rfried.dev@gmail.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/mvebu_crb_cn9130_defconfig b/configs/mvebu_crb_cn9130_defconfig
index f1215fa..62aeafc 100644
--- a/configs/mvebu_crb_cn9130_defconfig
+++ b/configs/mvebu_crb_cn9130_defconfig
@@ -41,6 +41,7 @@
 CONFIG_ENV_IS_IN_MMC=y
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_SYS_MMC_ENV_DEV=1
+CONFIG_ARP_TIMEOUT=200
 CONFIG_AHCI_MVEBU=y
 CONFIG_DM_I2C=y
 CONFIG_SYS_I2C_MVTWSI=y