hwmon: (corsair-psu) Fix fan rpm calculation

The correct fan rpm value is also a LINEAR11 value but without a factor.
Verified by using the fan test button on the psu to let the fan spin up
to maximum for some seconds.

Fixes: 933222c98445 ("hwmon: (corsair-psu) fix unintentional sign extension issue")
Signed-off-by: Wilken Gottwalt <wilken.gottwalt@posteo.net>
Link: https://lore.kernel.org/r/20201113121954.GA8488@monster.powergraphx.local
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/corsair-psu.c

@@ -252,12 +252,7 @@ static int corsairpsu_get_value(struct corsairpsu_data *priv, u8 cmd, u8 rail, l
 		*val = corsairpsu_linear11_to_int(tmp & 0xFFFF) * 1000;
 		break;
 	case PSU_CMD_FAN:
-		/*
-		 * this value is best guess, so the calculated value could be wrong, it is hard
-		 * to ge the fan to spin in these semi-passive power supplies, which need a
-		 * quite high load to do so
-		 */
-		*val = ((tmp & 0xFF) << 8) + ((tmp >> 8) & 0xFF);
+		*val = corsairpsu_linear11_to_int(tmp & 0xFFFF);
 		break;
 	case PSU_CMD_RAIL_WATTS:
 	case PSU_CMD_TOTAL_WATTS: