mke2fs: enable lazy_itable_init on newer kernel by default

mke2fs: enable lazy_itable_init on newer kernel by default

Currently is used did not specified lazy_itable_init option we rely on
information from ext4 module exported via sysfs interface. However if
the ext4 module is not loaded it will not be enabled even though kernel
might support it.

With this commit we set the default according to the kernel version,
however we still allow it to be set manually via extended option or be
enabled in case that ext4 module advertise that it supports this
feature.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>