mm/hugetlb: Use try_grab_folio() instead of try_grab_compound_head()

follow_hugetlb_page() only cares about success or failure, so it doesn't
need to know the type of the returned pointer, only whether it's NULL
or not.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>