powerpc/mm: remove flush_tlb_page_nohash

This should be same as flush_tlb_page except for hash32. For hash32
I guess the existing code is wrong, because we don't seem to be
flushing tlb for Hash != 0 case at all. Fix this by switching to
calling flush_tlb_page() which does the right thing by flushing
tlb for both hash and nohash case with hash32

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>