x86: Add an option to control the position of U-Boot

The existing work-around for positioning U-Boot in the ROM when it
actually runs from RAM still exists and there is not obvious way to change
this.

Add a proper Kconfig option to handle this case. This also adds a new bool
property to indicate whether CONFIG_SYS_TEXT_BASE exists.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/Kconfig b/Kconfig
index 92fc4fc..46a31f4 100644
--- a/Kconfig
+++ b/Kconfig
@@ -545,9 +545,14 @@
 	  configuration to Kconfig. Since this option will be removed sometime,
 	  new boards should not use this option.
 
-config SYS_TEXT_BASE
+config HAVE_SYS_TEXT_BASE
+	bool
 	depends on !NIOS2 && !XTENSA
 	depends on !EFI_APP
+	default y
+
+config SYS_TEXT_BASE
+	depends on HAVE_SYS_TEXT_BASE
 	default 0x80800000 if ARCH_OMAP2PLUS || ARCH_K3
 	default 0x4a000000 if ARCH_SUNXI && !MACH_SUN9I && !MACH_SUN8I_V3S
 	default 0x2a000000 if ARCH_SUNXI && MACH_SUN9I
@@ -556,8 +561,6 @@
 	help
 	  The address in memory that U-Boot will be running from, initially.
 
-
-
 config SYS_CLK_FREQ
 	depends on ARC || ARCH_SUNXI || MPC83xx
 	int "CPU clock frequency"