hwmon: (amc6821) Fix permissions for temp2_input

commit df86754b746e9a0ff6f863f690b1c01d408e3cdc upstream.

temp2_input should not be writable, fix it.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

	modified:   drivers/hwmon/amc6821.c
Change-Id: I9d059ac247b173b85e6030e06ea8a48067d932b8