Convert CONFIG_TPL_TEXT_BASE to Kconfig

This converts the following to Kconfig:
   CONFIG_TPL_TEXT_BASE

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/chromebook_samus_tpl_defconfig b/configs/chromebook_samus_tpl_defconfig
index 3cc25b5..c3c133b 100644
--- a/configs/chromebook_samus_tpl_defconfig
+++ b/configs/chromebook_samus_tpl_defconfig
@@ -8,6 +8,7 @@
 CONFIG_SPL_DM_SPI=y
 CONFIG_DEFAULT_DEVICE_TREE="chromebook_samus"
 CONFIG_SPL_TEXT_BASE=0xffe70000
+CONFIG_TPL_TEXT_BASE=0xfffd8000
 CONFIG_DEBUG_UART_BOARD_INIT=y
 CONFIG_DEBUG_UART_BASE=0x3f8
 CONFIG_DEBUG_UART_CLOCK=1843200