powerpc/spufs: Remove MAX_USER_PRIO define

Current ppc64_defconfig fails with:

 arch/powerpc/platforms/cell/spufs/sched.c:86:0: error: "MAX_USER_PRIO" redefined [-Werror]
 cc1: all warnings being treated as errors

Commit 6b6350f1 ("sched: Expose some macros related to priority")
introduced a generic MAX_USER_PRIO macro to sched/prio.h, which is
causing the conflit. Use that one instead of our own.
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NJeremy Kerr <jk@ozlabs.org>
Cc: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/1392098717.689604.970589769393.1.gpush@pabloSigned-off-by: NIngo Molnar <mingo@kernel.org>

arch/powerpc/platforms/cell/spufs/sched.c

@@ -83,7 +83,6 @@ static struct timer_list spuloadavg_timer;
 #define MIN_SPU_TIMESLICE	max(5 * HZ / (1000 * SPUSCHED_TICK), 1)
 #define DEF_SPU_TIMESLICE	(100 * HZ / (1000 * SPUSCHED_TICK))
 
-#define MAX_USER_PRIO		(MAX_PRIO - MAX_RT_PRIO)
 #define SCALE_PRIO(x, prio) \
 	max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO / 2), MIN_SPU_TIMESLICE)