drm/lima: support heap buffer creation

heap buffer is used as output of GP and input of PP for
Mali Utgard GPU. Size of heap buffer depends on the task
so is a runtime variable.

Previously we just create a large enough buffer as heap
buffer. Now we add a heap buffer type to be able to
increase the backup memory dynamically when GP fail due
to lack of heap memory.

Reviewed-by: Vasily Khoruzhick <anarsoul@gmail.com>
Tested-by: Andreas Baierl <ichgeh@imkreisrum.de>
Signed-off-by: Qiang Yu <yuq825@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200116131157.13346-4-yuq825@gmail.com

drivers/gpu/drm/lima/lima_drv.h

@@ -9,6 +9,7 @@
 #include "lima_ctx.h"
 
 extern int lima_sched_timeout_ms;
+extern uint lima_heap_init_nr_pages;
 
 struct lima_vm;
 struct lima_bo;