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/da850evm_defconfig b/configs/da850evm_defconfig
index ee49ed2..1a6a97e 100644
--- a/configs/da850evm_defconfig
+++ b/configs/da850evm_defconfig
@@ -40,6 +40,7 @@
 CONFIG_CMD_MTD=y
 # CONFIG_CMD_SF is not set
 # CONFIG_CMD_SETEXPR is not set
+CONFIG_BOOTP_DNS2=y
 # CONFIG_CMD_TIME is not set
 # CONFIG_CMD_EXT4 is not set
 CONFIG_CMD_FS_UUID=y