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/birdland_bav335a_defconfig b/configs/birdland_bav335a_defconfig
index 87dae59..2eb03ff 100644
--- a/configs/birdland_bav335a_defconfig
+++ b/configs/birdland_bav335a_defconfig
@@ -39,6 +39,7 @@
 CONFIG_CMD_USB=y
 CONFIG_CMD_USB_MASS_STORAGE=y
 # CONFIG_CMD_SETEXPR is not set
+CONFIG_BOOTP_DNS2=y
 CONFIG_CMD_EXT4_WRITE=y
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG=y