Convert CONFIG_BOOTP_DNS2 to Kconfig

This converts the following to Kconfig:
   CONFIG_BOOTP_DNS2
   CONFIG_BOOTP_PXE_CLIENTARCH

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/rut_defconfig b/configs/rut_defconfig
index 40c9de2..20b5f98 100644
--- a/configs/rut_defconfig
+++ b/configs/rut_defconfig
@@ -48,6 +48,7 @@
 CONFIG_CMD_USB=y
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_CMD_DHCP=y
+CONFIG_BOOTP_DNS2=y
 CONFIG_CMD_MII=y
 CONFIG_CMD_PING=y
 CONFIG_CMD_BMP=y