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/imx6ul_geam_mmc_defconfig b/configs/imx6ul_geam_mmc_defconfig
index 777ed3f..318628b 100644
--- a/configs/imx6ul_geam_mmc_defconfig
+++ b/configs/imx6ul_geam_mmc_defconfig
@@ -19,6 +19,7 @@
 CONFIG_BOOTDELAY=3
 CONFIG_SUPPORT_RAW_INITRD=y
 CONFIG_BOUNCE_BUFFER=y
+CONFIG_SPL_TEXT_BASE=0x00908000
 CONFIG_SPL_WATCHDOG_SUPPORT=y
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="geam6ul> "