drm: drop obsolete drm_core.h

drm: drop obsolete drm_core.h

The drm_core.h header contains a set of constants meant to be used
throughout DRM. However, as it turns out, they're each used just once and
don't bring any benefit. They're also grossly mis-named and lack
name-spacing. This patch inlines them, or moves them into drm_internal.h
as appropriate:

 - CORE_AUTHOR and CORE_DESC are inlined into corresponding MODULE_*()
   macros. It's just confusing having to follow 2 pointers when trying to
   find the definition of these fields. Grep'ping for MODULE_AUTHOR()
   should reveal the full information, if there's no strong reason not to.

 - CORE_NAME, CORE_DATE, CORE_MAJOR, CORE_MINOR, and CORE_PATCHLEVEL are
   inlined into the sysfs 'version' attribute. They're stripped
   everywhere else (which is just some printk() statements). CORE_NAME
   just doesn't make *any* sense, as we hard-code it in many places,
   anyway. The other constants are outdated and just serve
   binary-compatibility purposes. Hence, inline them in 'version' sysfs
   attribute (we might even try dropping it..).

 - DRM_IF_MAJOR and DRM_IF_MINOR are moved into drm_internal.h as they're
   only used by the global ioctl handlers. Furthermore, versioning
   interfaces breaks backports and as such is deprecated, anyway. We just
   keep them for historic reasons. I doubt anyone will ever modify them
   again.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20160901124837.680-6-dh.herrmann@gmail.com