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/tqma6q_mba6_mmc_defconfig b/configs/tqma6q_mba6_mmc_defconfig
index b4203da..1f16ba9 100644
--- a/configs/tqma6q_mba6_mmc_defconfig
+++ b/configs/tqma6q_mba6_mmc_defconfig
@@ -36,6 +36,7 @@
 CONFIG_ENV_OVERWRITE=y
 CONFIG_ENV_IS_IN_MMC=y
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
+CONFIG_ARP_TIMEOUT=200
 CONFIG_BOUNCE_BUFFER=y
 CONFIG_I2C_SET_DEFAULT_BUS_NUM=y
 CONFIG_SYS_I2C_MXC=y