configs: Migrate CONFIG_SYS_TEXT_BASE

On the NIOS2 and Xtensa architectures, we do not have
CONFIG_SYS_TEXT_BASE set.  This is a strict migration of the current
values into the defconfig and removing them from the headers.

I did not attempt to add more default values in and for now will leave
that to maintainers.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/zipitz2_defconfig b/configs/zipitz2_defconfig
index 515a313..b43ac19 100644
--- a/configs/zipitz2_defconfig
+++ b/configs/zipitz2_defconfig
@@ -1,5 +1,6 @@
 CONFIG_ARM=y
 CONFIG_TARGET_ZIPITZ2=y
+CONFIG_SYS_TEXT_BASE=0x0
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="console=tty0 console=ttyS2,115200 fbcon=rotate:3"
 # CONFIG_CONSOLE_MUX is not set