Convert CONFIG_HOSTNAME et al to Kconfig

This converts the following to Kconfig:
   CONFIG_GATEWAYIP
   CONFIG_HOSTNAME
   CONFIG_IPADDR
   CONFIG_NETMASK
   CONFIG_ROOTPATH
   CONFIG_SERVERIP
   CONFIG_UBOOTPATH

To do this, we introduce a CONFIG_USE_ form of each of the above and
change include/env_default.h to test for that to be set before setting a
value. Further, we don't want to stringify the IP address related values
as they are now properly strings via Kconfig.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/MPC8548CDS_legacy_defconfig b/configs/MPC8548CDS_legacy_defconfig
index d272ede..34d1938 100644
--- a/configs/MPC8548CDS_legacy_defconfig
+++ b/configs/MPC8548CDS_legacy_defconfig
@@ -15,6 +15,8 @@
 CONFIG_MPC85XX_HAVE_RESET_VECTOR=y
 CONFIG_ENABLE_36BIT_PHYS=y
 CONFIG_TARGET_MPC8548CDS_LEGACY=y
+CONFIG_USE_UBOOTPATH=y
+CONFIG_UBOOTPATH="8548cds/u-boot.bin"
 CONFIG_PCIE1=y
 CONFIG_SYS_MONITOR_LEN=524288
 CONFIG_OF_BOARD_SETUP=y
@@ -44,6 +46,17 @@
 CONFIG_BOOTFILE="8548cds/uImage.uboot"
 CONFIG_USE_ETHPRIME=y
 CONFIG_ETHPRIME="eTSEC0"
+CONFIG_USE_HOSTNAME=y
+CONFIG_USE_GATEWAYIP=y
+CONFIG_GATEWAYIP="192.168.1.1"
+CONFIG_USE_IPADDR=y
+CONFIG_IPADDR="192.168.1.253"
+CONFIG_USE_NETMASK=y
+CONFIG_NETMASK="255.255.255.0"
+CONFIG_USE_ROOTPATH=y
+CONFIG_ROOTPATH="/nfsroot"
+CONFIG_USE_SERVERIP=y
+CONFIG_SERVERIP="192.168.1.1"
 CONFIG_SPD_EEPROM=y
 CONFIG_CHIP_SELECTS_PER_CTRL=2
 CONFIG_DDR_ECC=y