riscv: mremap speedup - enable HAVE_MOVE_PUD and HAVE_MOVE_PMD

HAVE_MOVE_PUD enables remapping pages at the PUD level if both the source
and destination addresses are PUD-aligned.
HAVE_MOVE_PMD does similar speedup on the PMD level.

With HAVE_MOVE_PUD enabled, there is about a 143x improvement on qemu
With HAVE_MOVE_PMD enabled, there is about a 5x improvement on qemu

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>