android: camera_stream: Include <poll.h> instead of <sys/poll.h>

The standard C library header for the poll() API is poll.h, not
sys/poll.h. The musl C library warns about this:

In file included from src/android/camera_stream.cpp:13:
host/i586-buildroot-linux-musl/sysroot/usr/include/sys/poll.h:1:2: error: #warning redirecting incorrect #include <sys/poll.h> to <poll.h> [-Werror=cpp]
    1 | #warning redirecting incorrect #include <sys/poll.h> to <poll.h>
      |  ^~~~~~~

Fix it by including the correct header.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>

src/android/camera_stream.cpp

@@ -8,9 +8,9 @@
 #include "camera_stream.h"
 
 #include <errno.h>
+#include <poll.h>
 #include <string.h>
 #include <sys/mman.h>
-#include <sys/poll.h>
 #include <unistd.h>
 
 #include <libcamera/formats.h>