The unique minor limit of 255 will overflow easily in
some scenarios where eventfd needs to be create/destroy
frequently:
while (1)
{
fd = eventfd(0, 0); // minor++
sleep(1);
close(fd);
}
remove the unique minor limit.
Change-Id: I0ea1c825ce9b542c883166cb3e72574455ffdd0d
Signed-off-by: chao.an <anchao@xiaomi.com>