iio: light: tsl2772: fix reading proximity-diodes from device tree

tsl2772_read_prox_diodes() will correctly parse the properties from
device tree to determine which proximity diode(s) to read from, however
it didn't actually set this value on the struct tsl2772_settings. Let's
go ahead and fix that.

Reported-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/lkml/20230327120823.1369700-1-trix@redhat.com/
Fixes: 94cd111 ("iio: tsl2772: add support for reading proximity led settings from device tree")
Signed-off-by: Brian Masney <bmasney@redhat.com>
Link: https://lore.kernel.org/r/20230404011455.339454-1-bmasney@redhat.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Author: masneyb

drivers/iio/light/tsl2772.c

@@ -601,6 +601,7 @@ static int tsl2772_read_prox_diodes(struct tsl2772_chip *chip)
 			return -EINVAL;
 		}
 	}
+	chip->settings.prox_diode = prox_diode_mask;
 
 	return 0;
 }