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/MCR3000_defconfig b/configs/MCR3000_defconfig
index 7d54807..3e16ffc 100644
--- a/configs/MCR3000_defconfig
+++ b/configs/MCR3000_defconfig
@@ -55,6 +55,12 @@
 CONFIG_ENV_OVERWRITE=y
 CONFIG_ENV_IS_IN_FLASH=y
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
+CONFIG_USE_IPADDR=y
+CONFIG_IPADDR="192.168.0.3"
+CONFIG_USE_NETMASK=y
+CONFIG_NETMASK="255.0.0.0"
+CONFIG_USE_SERVERIP=y
+CONFIG_SERVERIP="192.168.0.1"
 CONFIG_SYS_BR0_PRELIM_BOOL=y
 CONFIG_SYS_BR0_PRELIM=0x4000801
 CONFIG_SYS_OR0_PRELIM=0xFFC00926