LoongArch: Use physical addresses for CSR_MERRENTRY/CSR_TLBRENTRY

LoongArch: Use physical addresses for CSR_MERRENTRY/CSR_TLBRENTRY

Now we use virtual addresses to fill CSR_MERRENTRY/CSR_TLBRENTRY, but
hardware hope physical addresses. Now it works well because the high
bits are ignored above PA_BITS (48 bits), but explicitly use physical
addresses can avoid potential bugs. So fix it.

Cc: stable@vger.kernel.org
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>