DEVFS - Modification of clone behaviour; general cleanup; xtime
* Use default_dev_ops by default for make_autoclone_dev so that opens
and other operations on it fail when it fails as a clone handler.
* Accept NULL as argument for bimtap for make_autoclone_dev, so that
there's no explicit need for a clone bitmap to use this function.
* Add destroy_autoclone_dev as a counterpart to make_autoclone_dev.
* Const-ify a bunch of char *
* Use kstrdup instead of kmalloc + memcpy magic at a few places where
this makes sense.
* Rework atime/mtime/ctime as advised by Simon Schubert on IRC.
* Clean up devfs_clone by getting rid of old code and return NULL
if cloning fails, else return the cloned device.
* Sync up all pending devfs operations just before calling into the
clone handler, so that issues with device deletion/creation are
dealt with appropriately.
* Change cloning in devfs_spec_open to match devfs_clone changes and
also check the return value of devfs_create_device_node, as it can
return NULL. If cloning fails, the cloning device will be opened,
which will have the default_ops and hence will fail returning
ENODEV.
* Cosmetic changes
Suggested-By: Simon "corecode" Schubert