bpfilter: don't pass O_CREAT when opening console for debug

Passing O_CREAT (00000100) to open means we should also pass file
mode as the third parameter.  Creating /dev/console as a regular
file may not be helpful anyway, so simply drop the flag when
opening debug_fd.

Fixes: d2ba09c1

 ("net: add skeleton of bpfilter kernel module")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>