idr: rename MAX_LEVEL to MAX_IDR_LEVEL

idr: rename MAX_LEVEL to MAX_IDR_LEVEL

To avoid name conflicts:

drivers/video/riva/fbdev.c:281:9: sparse: preprocessor token MAX_LEVEL redefined

While at it, also make the other names more consistent and add
parentheses.

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: walter harms <wharms@bfs.de>
Cc: Glauber Costa <glommer@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>