rtc: hym8563: Return -EINVAL if the time is known to be invalid

commit f236a2a2ebabad0848ad0995af7ad1dc7029e895 upstream.

The current code returns -EPERM when the voltage loss bit is set.
Since the bit indicates that the time value is not valid, return
-EINVAL instead, which is the appropriate error code for this
situation.

Fixes: dcaf03849352 ("rtc: add hym8563 rtc-driver")
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Link: https://lore.kernel.org/r/20191212153111.966923-1-paul.kocialkowski@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/rtc/rtc-hym8563.c b/drivers/rtc/rtc-hym8563.c
index e5ad527..a8c2d38 100644
--- a/drivers/rtc/rtc-hym8563.c
+++ b/drivers/rtc/rtc-hym8563.c
@@ -105,7 +105,7 @@
 
 	if (!hym8563->valid) {
 		dev_warn(&client->dev, "no valid clock/calendar values available\n");
-		return -EPERM;
+		return -EINVAL;
 	}
 
 	ret = i2c_smbus_read_i2c_block_data(client, HYM8563_SEC, 7, buf);