Move qemu-timer.h to include/qemu/timer.h

Note: upstream still puts qemu-timer.c in the top-level
directory, so no need to move it

Change-Id: I475309d6f0040b4fd2277e52a2526825c112e91f
diff --git a/qemu-char.c b/qemu-char.c
index 46c15ce..e2fea82 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -27,7 +27,7 @@
 #include "monitor.h"
 #include "console.h"
 #include "sysemu.h"
-#include "qemu-timer.h"
+#include "qemu/timer.h"
 #include "qemu-char.h"
 #include "block.h"
 #include "hw/usb.h"