[RFC PATCH] tty/serial: at91: disable uart timer at start of shutdown

[Mark Roszko]

**Sorry for the duplicate mail, I forgot to force plain-text mode in
gmail or the mailing list rejects the mails. Sigh, I need to buy my
own email server at this rate to even deal with the mailing lists and
proper etiquette (no quoteS) :(

Ah, I forgot there was that third mode(no dma and no pdc). Yea it's
probably a bad idea to play with fire and call del_timer_sync on a
non-initialized timer struct.

Alternatively to setting it up in all modes, the mode could also be
checked in _shutdown:
if ( ( atmel_use_dma_rx(port) || atmel_use_pdc_rx(port) )
           && !atmel_port->is_usart)
      del_timer_sync(&atmel_port->uart_timer);

But it doesn't hurt to call setup_timer in the other case either
because it just initializes the fields in timer_list. So I'm not sure
what best practices dictates here.

Commit messages looks fine, thanks for fixing that, I'm still getting
used to the linux dev process and I also do it at 3am at night.