rtc: gamecube: Add missing iounmap in gamecube_rtc_read_offset_from_sram

The hw_srnprot needs to be unmapped when gamecube_rtc_read_offset_from_sram returns.

Fixs: 8655940 (rtc: gamecube: Add a RTC driver for the GameCube, Wii and Wii U)
Signed-off-by: Yuan Can <[email protected]>
Signed-off-by: Alexandre Belloni <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: Yuan Can

drivers/rtc/rtc-gamecube.c

@@ -267,6 +267,7 @@ static int gamecube_rtc_read_offset_from_sram(struct priv *d)
 	ret = regmap_read(d->regmap, RTC_SRAM_BIAS, &d->rtc_bias);
 	if (ret) {
 		pr_err("failed to get the RTC bias\n");
+		iounmap(hw_srnprot);
 		return -1;
 	}