Fix two uninitialized variables in the v4l2 access module

Without this patch, the initial value on my system is for example 3, so that two much items are counted. In the second step the function breaks with a error code, when the information downloading of the non-existing item fails.
Signed-off-by: Alina Friedrichsen <x-alina@gmx.net>
Signed-off-by: Antoine Cellerier <dionoea@videolan.org>
(cherry picked from commit 288f193a)

modules/access/v4l2.c

@@ -2330,6 +2330,7 @@ static bool ProbeVideoDev( vlc_object_t *p_obj, demux_sys_t *p_sys,
     {
         struct v4l2_standard t_standards;
         t_standards.index = 0;
+        p_sys->i_standard = 0;
         while( v4l2_ioctl( i_fd, VIDIOC_ENUMSTD, &t_standards ) >=0 )
         {
             p_sys->i_standard++;
@@ -2393,6 +2394,7 @@ static bool ProbeVideoDev( vlc_object_t *p_obj, demux_sys_t *p_sys,
     {
         struct v4l2_tuner tuner;
         memset( &tuner, 0, sizeof(tuner) );
+        p_sys->i_tuner = 0;
         while( v4l2_ioctl( i_fd, VIDIOC_G_TUNER, &tuner ) >= 0 )
         {
             p_sys->i_tuner++;