powerpc: Fix corruption error in rh_alloc_fixed()

There is an error in rh_alloc_fixed() of the Remote Heap code:
If there is at least one free block blk won't be NULL at the end of the
search loop, so -ENOMEM won't be returned and the else branch of
"if (bs == s || be == e)" will be taken, corrupting the management
structures.

Signed-off-by: Guillaume Knispel <[e-mail]>
Acked-by: Timur Tabi <[e-mail]>
Signed-off-by: Kumar Gala <[e-mail]>

arch/powerpc/lib/rheap.c

···
 		be = blk->start + blk->size;
 		if (s >= bs && e <= be)
 			break;
+		blk = NULL;
 	}
 
 	if (blk == NULL)