chardev: remove context in chr_update_read_handler

We had a per-chardev cache for context, then we don't need this
parameter to be passed in every time when chr_update_read_handler()
called.  As long as we are calling chr_update_read_handler() using
qemu_chr_be_update_read_handlers() we'll be fine.

Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <1505975754-21555-5-git-send-email-peterx@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/chardev/char-socket.c b/chardev/char-socket.c
index ee71cbe..e65148f 100644
--- a/chardev/char-socket.c
+++ b/chardev/char-socket.c
@@ -521,8 +521,7 @@
     qemu_chr_be_event(chr, CHR_EVENT_OPENED);
 }
 
-static void tcp_chr_update_read_handler(Chardev *chr,
-                                        GMainContext *context)
+static void tcp_chr_update_read_handler(Chardev *chr)
 {
     SocketChardev *s = SOCKET_CHARDEV(chr);