iio: event_monitor: add pitch, yaw and roll modifiers

Following the introduction of pitch, yaw and roll IIO modifiers, update the
event_monitor tool accordingly.

Signed-off-by: Andrea Merello <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

tools/iio/iio_event_monitor.c

···
 	[IIO_MOD_LINEAR_X] = "linear_x",
 	[IIO_MOD_LINEAR_Y] = "linear_y",
 	[IIO_MOD_LINEAR_Z] = "linear_z",
+	[IIO_MOD_PITCH] = "pitch",
+	[IIO_MOD_YAW] = "yaw",
+	[IIO_MOD_ROLL] = "roll",
 };
 
 static bool event_is_known(struct iio_event_data *event)