watchdog: f71808e_wdt: Fix WD_EN register read

commit 977f6f68331f94bb72ad84ee96b7b87ce737d89d upstream.

F71808FG_FLAG_WD_EN defines bit position, not a bitmask

Signed-off-by: Igor Pylypiv <igor.pylypiv@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>