Merge: Fix for "serial: 8250: Toggle IER bits on only after irq has been setup"

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/4263

JIRA: INTERNAL  
Upstream Status: RHEL only 

This patch somehow added the same code that was already there, removing
the offending patch.
    
Signed-off-by: Lucas Zampieri <lzampier@redhat.com>

Approved-by: John W. Linville <linville@redhat.com>
Approved-by: Benjamin Coddington <bcodding@redhat.com>
Approved-by: Ivan Vecera <ivecera@redhat.com>
Approved-by: Scott Weaver <scweaver@redhat.com>
Approved-by: Michal Schmidt <mschmidt@redhat.com>
Approved-by: Petr Oros <poros@redhat.com>
Approved-by: Prarit Bhargava <prarit@redhat.com>
Approved-by: Andrew Halaney <ahalaney@redhat.com>

Merged-by: Lucas Zampieri <lzampier@redhat.com>

Author: zampierilucas

drivers/tty/serial/8250/8250_port.c

@@ -2334,10 +2334,6 @@ int serial8250_do_startup(struct uart_port *port)
 	if (retval)
 		goto out;
 
-	retval = up->ops->setup_irq(up);
-	if (retval)
-		goto out;
-
 	if (port->irq && !(up->port.flags & UPF_NO_THRE_TEST)) {
 		unsigned char iir1;