libcamera: Correct include headers for Mutex classes

Mutex classes are defined in mutex.h. This replaces thread.h
include for the Mutex classes with mutex.h.

Signed-off-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/v4l2/v4l2_compat.cpp

@@ -14,6 +14,8 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 
+#include <libcamera/base/utils.h>
+
 #define LIBCAMERA_PUBLIC __attribute__((visibility("default")))
 
 using namespace libcamera;