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/am3517_evm_defconfig b/configs/am3517_evm_defconfig
index 25b46f4..b9f59f3 100644
--- a/configs/am3517_evm_defconfig
+++ b/configs/am3517_evm_defconfig
@@ -12,6 +12,7 @@
 CONFIG_BOOTDELAY=10
 # CONFIG_USE_BOOTCOMMAND is not set
 CONFIG_VERSION_VARIABLE=y
+CONFIG_SPL_TEXT_BASE=0x40200000
 CONFIG_SPL_SYS_MALLOC_SIMPLE=y
 # CONFIG_SPL_FS_EXT4 is not set
 CONFIG_SPL_MTD_SUPPORT=y