riscv: tlb: fix __p*d_free_tlb()

If non-leaf PTEs I.E pmd, pud or p4d is modified, a sfence.vma is
a must for safe, imagine if an implementation caches the non-leaf
translation in TLB, although I didn't meet this HW so far, but it's
possible in theory.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Fixes: c5e9b2c2

 ("riscv: Improve tlb_flush()")
Link: https://lore.kernel.org/r/20231219175046.2496-2-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>