drm: add drm_dev_alloc() helper

Instead of managing device allocation+initialization in each bus-driver,
we should do that in a central place. drm_fill_in_dev() already does most
of it, but also requires the global drm lock for partial AGP device
registration.

Split both apart so we have a clean device initialization/allocation
phase, and a registration phase.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
drm: merge device setup into drm_dev_register()

All bus drivers do device setup themselves. This requires us to adjust all
of them if we introduce new core features. Thus, merge all these into a
uniform drm_dev_register() helper.

Note that this removes the drm_lastclose() error path for AGP as it is
horribly broken. Moreover, no bus driver called this in any other error
path either. Instead, we use the recently introduced AGP cleanup helpers.

We also keep a DRIVER_MODESET condition around pci_set_drvdata() to keep
semantics.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
drm: move drm_lastclose() to drm_fops.c

Try to keep all functions that handle DRM file_operations in drm_fops.c
so internal helpers can be marked static later.

This makes the split between the 3 core files more obvious:
 - drm_stub.c: DRM device allocation/destruction and management
 - drm_fops.c: DRM file_operations (except for ioctl)
 - drm_drv.c: Global DRM init + ioctl handling
Well, ioctl handling is still spread throughout hundreds of source files,
but at least the others are clearly defined this way.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
drm: introduce drm_dev_free() to fix error paths

The error paths in DRM bus drivers currently leak memory as they don't
correctly revert drm_dev_alloc(). Introduce drm_dev_free() to free DRM
devices which haven't been registered, yet.

We must be careful not to introduce any side-effects with cleanups done in
drm_dev_free(). drm_ht_remove(), drm_ctxbitmap_cleanup() and
drm_gem_destroy() are all fine in that regard.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
drm: move device unregistration into drm_dev_unregister()

Analog to drm_dev_register(), we now provide drm_dev_unregister() which
does the reverse. drm_dev_put() is still in place and combines the calls
to drm_dev_unregister() and drm_dev_free() so buses don't have to change.

*_get() and *_put() are used for reference-counting in the kernel.
However, drm_dev_put() definitely does not do any kind of ref-counting.
Hence, use the more appropriate *_register(), *_unregister(), *_alloc()
and *_free() names.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>