prandom: Remove unused include

prandom.h doesn't use percpu.h - this fixes some circular header issues.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>

include/linux/prandom.h

@@ -10,7 +10,6 @@
 
 #include <linux/types.h>
 #include <linux/once.h>
-#include <linux/percpu.h>
 #include <linux/random.h>
 
 struct rnd_state {