drm: cleanup use of Linux list handling macros

This makes the drms use of the list handling macros a lot cleaner
and more along the lines of how they should be used and uses them
in some more places.

Signed-off-by: Dave Airlie <airlied@linux.ie>

drivers/char/drm/drm_memory.c

diff --git a/drivers/char/drm/drm_memory.c b/drivers/char/drm/drm_memory.c
index 92a8670..0683334 100644
--- a/drivers/char/drm/drm_memory.c
+++ b/drivers/char/drm/drm_memory.c
@@ -94,7 +94,7 @@
 	offset -= dev->hose->mem_space->start;
 #endif
 
-	for (agpmem = dev->agp->memory; agpmem; agpmem = agpmem->next)
+	list_for_each_entry(agpmem, &dev->agp->memory, head)
 		if (agpmem->bound <= offset
 		    && (agpmem->bound + (agpmem->pages << PAGE_SHIFT)) >=
 		    (offset + size))