Documentation: gpio: legacy: Don't use POLLERR for poll(2)

According to the manpage of poll(2) and also looking at the respective
syscall providing POLLERR in .events is a no-op. So don't recommend
using it.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/driver-api/gpio/legacy.rst

@@ -690,11 +690,10 @@ and have the following read/write attributes:
 		and if it has been configured to generate interrupts (see the
 		description of "edge"), you can poll(2) on that file and
 		poll(2) will return whenever the interrupt was triggered. If
-		you use poll(2), set the events POLLPRI and POLLERR. If you
-		use select(2), set the file descriptor in exceptfds. After
-		poll(2) returns, either lseek(2) to the beginning of the sysfs
-		file and read the new value or close the file and re-open it
-		to read the value.
+		you use poll(2), set the events POLLPRI. If you use select(2),
+		set the file descriptor in exceptfds. After poll(2) returns,
+		either lseek(2) to the beginning of the sysfs file and read the
+		new value or close the file and re-open it to read the value.
 
 	"edge" ... reads as either "none", "rising", "falling", or
 		"both". Write these strings to select the signal edge(s)