serial: pmac_zilog: add sparse context annotation

Add sparse context annotation to the receive handler, which releases and
reacquires the port lock, to silence a sparse warning:

	drivers/tty/serial/pmac_zilog.c:255:36: sparse: sparse: context imbalance in 'pmz_receive_chars' - unexpected unlock

Reported-by: kernel test robot <[email protected]>
Signed-off-by: Johan Hovold <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: jhovold

drivers/tty/serial/pmac_zilog.c

@@ -213,6 +213,7 @@ static void pmz_interrupt_control(struct uart_pmac_port *uap, int enable)
 }
 
 static bool pmz_receive_chars(struct uart_pmac_port *uap)
+	__must_hold(&uap->port.lock)
 {
 	struct tty_port *port;
 	unsigned char ch, r1, drop, flag;