drm: Consolidate memory allocation types

* The DRM subsystem was using many different kmalloc types for no
  good reason

* Some types were only used twice (1x kmalloc() and 1x kfree() calls)

* Remove that useless complexity and only keep one kmalloc type for
  the whole DRM subsystem and its drivers

Inspired-by: OpenBSD
drm: Add and use drm/drm_mem_util.h

Reducing differences with the Linux code base
Removing screensaver modules from build
Removing splash code from syscons
Remove most of the screen saver code
ripping out SC_PIXEL_MODE
Removing font handling from syscons.
Removing mouse cut/paste support fron syscons
Remove mouse cursor handling. Remove fontsize and screensize stuff.
Remove (ega_)palette. Reduce scmmap to a stub.
Adding call to sc_hist_restore that I accidentally removed in a previous commit.
moving sc_get_cons_priority, sc_get_bios_values and sc_tone from syscons_isa.c to syscons.c
Moved sc_get_softc and sc_max_unit from syscons_isa.c to syscons.c. Using SYSINIT to call sc_attach_unit.
Adding initial prototype of the txtdev code
Starting to implement the txtdev interface
First attempt at using the txtdev interface from syscons for drawing characters.
Fixing silly typo
Fix embarassing typos
Eliminating VTB_FRAMEBUFFER and scp->scr. Output is slightly broken now.
Moved most of the cursor handling code to txtdev.