powerpc/mm: Enable compound page check for both THP and HugeTLB

THP config results in compound pages. Make sure the kernel enables
the PageCompound() check with CONFIG_HUGETLB_PAGE disabled and
CONFIG_TRANSPARENT_HUGEPAGE enabled.

This makes sure we correctly flush the icache with THP pages.
flush_dcache_icache_page only matter for platforms that don't support
COHERENT_ICACHE.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210203045812.234439-1-aneesh.kumar@linux.ibm.com