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/mx31pdk_defconfig b/configs/mx31pdk_defconfig
index 910ad02..7eb07e6 100644
--- a/configs/mx31pdk_defconfig
+++ b/configs/mx31pdk_defconfig
@@ -9,6 +9,7 @@
 CONFIG_NR_DRAM_BANKS=1
 CONFIG_SPL=y
 # CONFIG_SPL_FRAMEWORK is not set
+CONFIG_SPL_TEXT_BASE=0x87dc0000
 CONFIG_SPL_NAND_SUPPORT=y
 # CONFIG_AUTO_COMPLETE is not set
 CONFIG_CMD_BOOTZ=y