Convert CONFIG_BIOSEMU to Kconfig

This converts the following to Kconfig:
   CONFIG_BIOSEMU

Cc: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Rini <trini@konsulko.com>

board/google/Kconfig

@@ -4,12 +4,16 @@
 
 if VENDOR_GOOGLE
 
+config BIOSEMU
+	bool
+
 choice
 	prompt "Mainboard model"
 	optional
 
 config TARGET_CHROMEBOOK_CORAL
 	bool "Chromebook coral"
+	select BIOSEMU
 	help
 	  This is a range of Intel-based laptops released in 2018. They use an
 	  Intel Apollo Lake SoC. The design supports WiFi, 4GB to 16GB of
@@ -24,6 +28,7 @@ config TARGET_CHROMEBOOK_CORAL
 
 config TARGET_CHROMEBOOK_LINK
 	bool "Chromebook link"
+	select BIOSEMU
 	help
 	  This is the Chromebook Pixel released in 2013. It uses an Intel
 	  i5 Ivybridge which is a die-shrink of Sandybridge, with 4GB of
@@ -36,6 +41,7 @@ config TARGET_CHROMEBOOK_LINK
 
 config TARGET_CHROMEBOOK_LINK64
 	bool "Chromebook link 64-bit"
+	select BIOSEMU
 	help
 	  This is the Chromebook Pixel released in 2013. With this config
 	  U-Boot is built as a 64-bit binary. This allows testing while this
@@ -43,6 +49,7 @@ config TARGET_CHROMEBOOK_LINK64
 
 config TARGET_CHROMEBOX_PANTHER
 	bool "Chromebox panther (not available)"
+	select BIOSEMU
 	help
 	  Note: At present this must be used with coreboot. See README.x86
 	  for instructions.

include/configs/chromebook_samus.h

@@ -15,9 +15,6 @@
 #include <configs/x86-common.h>
 #include <configs/x86-chromebook.h>
 
-/* We can rely on running natively, and this saves code size */
-#undef CONFIG_BIOSEMU
-
 #undef CONFIG_STD_DEVICES_SETTINGS
 #define CONFIG_STD_DEVICES_SETTINGS     "stdin=usbkbd,i8042-kbd,serial\0" \
 					"stdout=vidconsole,serial\0" \

include/configs/x86-chromebook.h

@@ -24,7 +24,6 @@
 #define CONFIG_PCI_IO_PHYS	CONFIG_PCI_IO_BUS
 #define CONFIG_PCI_IO_SIZE	0xefff
 
-#define CONFIG_BIOSEMU
 #define VIDEO_IO_OFFSET				0
 #define CONFIG_X86EMU_RAW_IO