radix tree test suite: Remove mempool

The radix tree hasn't used a mempool since the beginning of git history.
Remove the userspace mempool implementation.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Rehas Sachdeva <aquannie@gmail.com>

tools/testing/radix-tree/linux/mempool.h

@@ -1,16 +0,0 @@
-
-#include <linux/slab.h>
-
-typedef void *(mempool_alloc_t)(int gfp_mask, void *pool_data);
-typedef void (mempool_free_t)(void *element, void *pool_data);
-
-typedef struct {
-	mempool_alloc_t *alloc;
-	mempool_free_t *free;
-	void *data;
-} mempool_t;
-
-void *mempool_alloc(mempool_t *pool, int gfp_mask);
-void mempool_free(void *element, mempool_t *pool);
-mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
-			mempool_free_t *free_fn, void *pool_data);