drm/ttm: fix type mismatch error on sparc64

On sparc64, __fls() returns an "int", but the drm TTM code expected it
to be "unsigned long" as on x86.  As a result, on sparc (and arc, and
m68k) you get build errors because 'min()' checks that the types match.

As suggested by Linus, it can use min_t instead of min to force the type
to be "unsigned int".
Suggested-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NHuang Rui <ray.huang@amd.com>
Reviewed-by: NChristian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexdeucher@gmail.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/gpu/drm/ttm/ttm_pool.c

@@ -383,7 +383,8 @@ int ttm_pool_alloc(struct ttm_pool *pool, struct ttm_tt *tt,
 	else
 		gfp_flags |= GFP_HIGHUSER;
 
-	for (order = min(MAX_ORDER - 1UL, __fls(num_pages)); num_pages;
+	for (order = min_t(unsigned int, MAX_ORDER - 1, __fls(num_pages));
+	     num_pages;
 	     order = min_t(unsigned int, order, __fls(num_pages))) {
 		bool apply_caching = false;
 		struct ttm_pool_type *pt;