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/A20-Olimex-SOM-EVB_defconfig b/configs/A20-Olimex-SOM-EVB_defconfig
index 59dfdcc..bad6911 100644
--- a/configs/A20-Olimex-SOM-EVB_defconfig
+++ b/configs/A20-Olimex-SOM-EVB_defconfig
@@ -13,6 +13,7 @@
 CONFIG_SATAPWR="PC3"
 CONFIG_AHCI=y
 # CONFIG_SYS_MALLOC_CLEAR_ON_INIT is not set
+CONFIG_SPL_TEXT_BASE=0x60
 CONFIG_SPL_I2C_SUPPORT=y
 # CONFIG_CMD_FLASH is not set
 # CONFIG_SPL_DOS_PARTITION is not set