[SPARC64] mm: simpler tlb_flush_mmu

Minor simplification to the sparc64 tlb_flush_mmu: tlb_remove_page
set need_flush only after handling the tlb_fast_mode case, then
tlb_flush_mmu need not consider whether it's tlb_fast_mode.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: David S. Miller <davem@davemloft.net>