x86: Kconfig: Remove deprecated CONFIG_SYS_EXTRA_OPTIONS

Currently all x86 boards still use CONFIG_SYS_EXTRA_OPTIONS to define
the text base address. Since it is deprecated, just remove it and use
CONFIG_SYS_TEXT_BASE directly.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/board/google/chromebox_panther/Kconfig b/board/google/chromebox_panther/Kconfig
index 11df55a..e3604eb 100644
--- a/board/google/chromebox_panther/Kconfig
+++ b/board/google/chromebox_panther/Kconfig
@@ -12,6 +12,9 @@
 config SYS_CONFIG_NAME
 	default "chromebox_panther"
 
+config SYS_TEXT_BASE
+	default 0xfff00000
+
 # Panther actually uses haswell, not ivybridge, so this is just a placeholder
 config BOARD_SPECIFIC_OPTIONS # dummy
 	def_bool y