tools: fix compilation after gfp_types.h split

When gfp_types.h was split from gfp.h, it broke the radix test suite. Fix
the test suite by using gfp_types.h in the tools gfp.h header.

Link: https://lkml.kernel.org/r/20220902191923.1735933-1-willy@infradead.org
Fixes: cb5a065b4ea9 (headers/deps: mm: Split <linux/gfp_types.h> out of <linux/gfp.h>)
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reported-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>