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/portl2_defconfig b/configs/portl2_defconfig
index 7db4110..1b27e41 100644
--- a/configs/portl2_defconfig
+++ b/configs/portl2_defconfig
@@ -1,5 +1,6 @@
 CONFIG_ARM=y
 CONFIG_KIRKWOOD=y
+CONFIG_SYS_TEXT_BASE=0x07d00000
 CONFIG_TARGET_KM_KIRKWOOD=y
 CONFIG_IDENT_STRING="\nKeymile Port-L2"
 CONFIG_SYS_EXTRA_OPTIONS="KM_PORTL2"