v4l2: include <linux/ioctl.h> instead of <sys/ioctl.h>

Being a wrapper around <linux/ioctl.h>, <sys/ioctl.h> brings
no benefits for parser of VIDIOC_* ioctls.

* v4l2.c: Include <linux/ioctl.h> instead of <sys/ioctl.h>.
diff --git a/v4l2.c b/v4l2.c
index 1df4ca5..ab9a69c 100644
--- a/v4l2.c
+++ b/v4l2.c
@@ -39,7 +39,7 @@
 #include DEF_MPERS_TYPE(struct_v4l2_standard)
 
 #include <stdint.h>
-#include <sys/ioctl.h>
+#include <linux/ioctl.h>
 #include <linux/types.h>
 #include <linux/videodev2.h>