configs: move CONFIG_SPL_TEXT_BASE to Kconfig

Moved CONFIG_SPL_TEXT_BASE to common/spl/Kconfig and migrate existing
values.

Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
[trini: Re-run migration]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/colibri_t20_defconfig b/configs/colibri_t20_defconfig
index 0f4a04b..15fb955 100644
--- a/configs/colibri_t20_defconfig
+++ b/configs/colibri_t20_defconfig
@@ -9,6 +9,7 @@
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_DISPLAY_BOARDINFO_LATE=y
 CONFIG_ARCH_MISC_INIT=y
+CONFIG_SPL_TEXT_BASE=0x00108000
 CONFIG_SYS_PROMPT="Colibri T20 # "
 # CONFIG_CMD_IMI is not set
 CONFIG_CMD_DFU=y