iio: light: veml6070: fix veml6070_read() return value

veml6070_read() computes the sensor value in ret but
returns 0 instead of the actual result. This causes
veml6070_read_raw() to always report 0.

Return the computed value instead of 0.

Running make W=1 returns no errors. I was unable
to test the patch because I do not have the hardware.
Found by code inspection.

Fixes: fc38525135dd ("iio: light: veml6070: use guard to handle mutex")
Signed-off-by: Aldo Conte <[e-mail]>
Reviewed-by: Nuno Sá <[e-mail]>
Cc: <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/light/veml6070.c

···
 	if (ret < 0)
 		return ret;
 
-	ret = (msb << 8) | lsb;
-
-	return 0;
+	return (msb << 8) | lsb;
 }
 
 static const struct iio_chan_spec veml6070_channels[] = {