gpiolib: cdev: Fix typo in kernel doc for struct line

When eflags has been renamed to the edflags, the kernel doc change were
missed. Update kernel doc accordingly.

Fixes: b1a92e94 ("gpiolib: cdev: consolidate edge detector configuration flags")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Kent Gibson <warthog618@gmail.com>