x86: dfi: Add option to select different config headers for baseboards

This patch adds the infrastructure to define different config headers
with different configurations and default environment for the baseboards
that can now be selected via Kconfig. The new configuration for the
theadorable-x86-dfi-bt700 is also added.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Cc: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/configs/dfi-bt700-q7x-151_defconfig b/configs/dfi-bt700-q7x-151_defconfig
index 13d911c..bcc830a 100644
--- a/configs/dfi-bt700-q7x-151_defconfig
+++ b/configs/dfi-bt700-q7x-151_defconfig
@@ -1,13 +1,13 @@
 CONFIG_X86=y
 CONFIG_VENDOR_DFI=y
 CONFIG_DEFAULT_DEVICE_TREE="dfi-bt700-q7x-151"
-CONFIG_TARGET_DFI_BT700=y
-CONFIG_DEBUG_UART=y
 CONFIG_SMP=y
 CONFIG_HAVE_VGA_BIOS=y
+CONFIG_VGA_BIOS_ADDR=0xfffa0000
 CONFIG_GENERATE_PIRQ_TABLE=y
 CONFIG_GENERATE_MP_TABLE=y
 CONFIG_GENERATE_ACPI_TABLE=y
+CONFIG_HAVE_ACPI_RESUME=y
 CONFIG_SEABIOS=y
 CONFIG_FIT=y
 CONFIG_FIT_SIGNATURE=y
@@ -44,8 +44,6 @@
 CONFIG_DM_I2C=y
 CONFIG_NUVOTON_NCT6102D=y
 CONFIG_E1000=y
-CONFIG_DEBUG_UART_BASE=0x3f8
-CONFIG_DEBUG_UART_CLOCK=1843200
 CONFIG_USB_STORAGE=y
 CONFIG_USB_KEYBOARD=y
 CONFIG_FRAMEBUFFER_SET_VESA_MODE=y