drm/format-helper: Rework format-helper memcpy functions

Move destination-buffer clipping from all format-helper memcpy
function into callers. Support destination-buffer pitch. Only
distinguish between system and I/O memory, but use same logic
everywhere.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Tested-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20211110103702.374-3-tzimmermann@suse.de