smbios: move smbios code into a common folder

To share smbios among different architectures, this patch moves SMBIOS
code (smbios.c and smbios.h) from x86 specific folders into new
hw/smbios directories. As a result, CONFIG_SMBIOS=y is defined in
x86 default config files.

Acked-by: Gabriel Somlo <somlo@cmu.edu>
Tested-by: Gabriel Somlo <somlo@cmu.edu>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Leif Lindholm <leif.lindholm@linaro.org>
Signed-off-by: Wei Huang <wei@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/arch_init.c b/arch_init.c
index 725c638..38f5fb9 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -26,7 +26,7 @@
 #include "sysemu/arch_init.h"
 #include "hw/pci/pci.h"
 #include "hw/audio/audio.h"
-#include "hw/i386/smbios.h"
+#include "hw/smbios/smbios.h"
 #include "qemu/config-file.h"
 #include "qemu/error-report.h"
 #include "qmp-commands.h"