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/arch/x86/Kconfig b/arch/x86/Kconfig
index a2da080..93f1c77 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -924,8 +924,8 @@
 
 config X86_OFFSET_U_BOOT
 	hex "Offset of U-Boot in ROM image"
-	depends on HAVE_SYS_TEXT_BASE
-	default SYS_TEXT_BASE
+	depends on HAVE_TEXT_BASE
+	default TEXT_BASE
 
 config X86_OFFSET_SPL
 	hex "Offset of SPL in ROM image"