Rename CONFIG_SYS_TEXT_BASE to CONFIG_TEXT_BASE

The current name is inconsistent with SPL which uses CONFIG_SPL_TEXT_BASE
and this makes it imposible to use CONFIG_VAL().

Rename it to resolve this problem.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/imgtec/malta/Kconfig b/board/imgtec/malta/Kconfig
index 98eb4d1..4d124b3 100644
--- a/board/imgtec/malta/Kconfig
+++ b/board/imgtec/malta/Kconfig
@@ -9,7 +9,7 @@
 config SYS_CONFIG_NAME
 	default "malta"
 
-config SYS_TEXT_BASE
+config TEXT_BASE
 	default 0xbe000000 if 32BIT
 	default 0xffffffffbe000000 if 64BIT