v4l2: do not poll for POLLPRI

We do not dequeue those events. That could cause busy loops.

modules/access/v4l2/access.c

@@ -218,7 +218,7 @@ static block_t *AccessRead( access_t *access )
 
     struct pollfd fd;
     fd.fd = sys->fd;
-    fd.events = POLLIN|POLLPRI;
+    fd.events = POLLIN;
     fd.revents = 0;
 
     /* Wait for data */

modules/access/v4l2/demux.c

@@ -488,7 +488,7 @@ static void *StreamThread (void *data)
     struct pollfd ufd[1];
 
     ufd[0].fd = fd;
-    ufd[0].events = POLLIN | POLLPRI;
+    ufd[0].events = POLLIN;
 
     for (;;)
     {
@@ -523,7 +523,7 @@ static void *ReadThread (void *data)
     struct pollfd ufd[1];
 
     ufd[0].fd = fd;
-    ufd[0].events = POLLIN | POLLPRI;
+    ufd[0].events = POLLIN;
 
     for (;;)
     {