chardev: move headers to include/chardev

So they are all in one place. The following patch will move serial &
parallel declarations to the respective headers.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
diff --git a/chardev/char-socket.c b/chardev/char-socket.c
index e2fb7f7..ccc499c 100644
--- a/chardev/char-socket.c
+++ b/chardev/char-socket.c
@@ -22,14 +22,14 @@
  * THE SOFTWARE.
  */
 #include "qemu/osdep.h"
-#include "sysemu/char.h"
+#include "chardev/char.h"
 #include "io/channel-socket.h"
 #include "io/channel-tls.h"
 #include "qemu/error-report.h"
 #include "qapi/error.h"
 #include "qapi/clone-visitor.h"
 
-#include "char-io.h"
+#include "chardev/char-io.h"
 
 /***********************************************************/
 /* TCP Net console */