MIPS: add CONFIG_VIRTUALIZATION for virtio support

Add CONFIG_VIRTUALIZATION to the MIPS architecture and include the
the virtio code there. Used to enable the virtio drivers under QEMU.
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2002/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

@@ -2421,4 +2421,20 @@ source "security/Kconfig"
 
 source "crypto/Kconfig"
 
+menuconfig VIRTUALIZATION
+	bool "Virtualization"
+	default n
+	---help---
+	  Say Y here to get to see options for using your Linux host to run other
+	  operating systems inside virtual machines (guests).
+	  This option alone does not add any kernel code.
+
+	  If you say N, all options in this submenu will be skipped and disabled.
+
+if VIRTUALIZATION
+
+source drivers/virtio/Kconfig
+
+endif # VIRTUALIZATION
+
 source "lib/Kconfig"