mm: remove redundant condition for THP folio

mm: remove redundant condition for THP folio

folio_test_pmd_mappable() implies folio_test_large(), therefore, simplify
the expression for is_thp.

Link: https://lkml.kernel.org/r/20241018094151.3458-1-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>