sched, powerpc: Fix sched.h split-up build failure

Fix PowerPC/Cell build fallout from:

  8bd75c77 sched/rt: Move rt specific bits into new header file
Reported-by: NMichael Ellerman <michael@ellerman.id.au>
Cc: Clark Williams <williams@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20130207094707.7b9f825f@riff.lanSigned-off-by: NIngo Molnar <mingo@kernel.org>

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

@@ -24,6 +24,7 @@
 
 #include <linux/errno.h>
 #include <linux/sched.h>
+#include <linux/sched/rt.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/slab.h>