tty: fix console_sem lock order

vgacon_do_font_op releases and reacquires the BTM while holding
console_sem. This violates the rule that BTM has to be the
outer lock whenever we hold both.

There does not seem to be any reason to give up the BTM here,
so just stop doing that.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/video/console/vgacon.c

@@ -1108,7 +1108,6 @@ static int vgacon_do_font_op(struct vgastate *state,char *arg,int set,int ch512)
 		charmap += 4 * cmapsz;
 #endif
 
-	tty_unlock();
 	spin_lock_irq(&vga_lock);
 	/* First, the Sequencer */
 	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x1);
@@ -1192,7 +1191,6 @@ static int vgacon_do_font_op(struct vgastate *state,char *arg,int set,int ch512)
 		vga_wattr(state->vgabase, VGA_AR_ENABLE_DISPLAY, 0);	
 	}
 	spin_unlock_irq(&vga_lock);
-	tty_lock();
 	return 0;
 }