m68k: move CONFIG_SYS_TEXT_BASE to defconfig files

For historical reason, CONFIG_SYS_TEXT_BASE has been specified
in various ways:

[1] by board/${VENDOR}/${BOARD}/config.mk

[2] by CONFIG_SYS_EXTRA_OPTIONS
    (This was "options" field of boards.cfg before Kconfig conversion)

[3] by include/configs/${BOARD}.h

[4] by configs/${BOARD}_defconfig

Most of M68K boards use either [1] or [2], both of which we want to
deprecate.  Switch them into [4], which is the newest way (Kconfig).

We still allow [3] too, because it is still used by many boards and
we expect much time for conversion.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Angelo Dureghello <angelo at sysam.it>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/Kconfig b/Kconfig
index 821b464..9b07838 100644
--- a/Kconfig
+++ b/Kconfig
@@ -208,7 +208,8 @@
 	  new boards should not use this option.
 
 config SYS_TEXT_BASE
-	depends on SPARC || ARC || X86 || ARCH_UNIPHIER || ARCH_ZYNQMP
+	depends on SPARC || ARC || X86 || ARCH_UNIPHIER || ARCH_ZYNQMP || \
+		(M68K && !TARGET_ASTRO_MCF5373L)
 	depends on !EFI_APP
 	hex "Text Base"
 	help