vt: selection, fix double lock introduced by a merge

The merge commit cb05c6c (Merge 5.6-rc5 into tty-next) introduced a
double lock to set_selection_kernel. vc_sel.lock is locked both in
set_selection_kernel and its callee __set_selection_kernel now.

Remove the latter.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/r/20200316064544.4799-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/vt/selection.c

@@ -219,7 +219,6 @@ static int __set_selection_kernel(struct tiocl_selection *v, struct tty_struct *
 	if (ps > pe)	/* make vc_sel.start <= vc_sel.end */
 		swap(ps, pe);
 
-	mutex_lock(&vc_sel.lock);
 	if (vc_sel.cons != vc_cons[fg_console].d) {
 		clear_selection();
 		vc_sel.cons = vc_cons[fg_console].d;