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/intel/minnowmax/Kconfig b/board/intel/minnowmax/Kconfig
index 43c50a5..f2a0b71 100644
--- a/board/intel/minnowmax/Kconfig
+++ b/board/intel/minnowmax/Kconfig
@@ -12,6 +12,9 @@
 config SYS_CONFIG_NAME
 	default "minnowmax"
 
+config SYS_TEXT_BASE
+	default 0xfff00000
+
 config BOARD_SPECIFIC_OPTIONS # dummy
 	def_bool y
 	select X86_RESET_VECTOR