LoongArch: KVM: Use CSR_CRMD_PLV in kvm_arch_vcpu_in_kernel()

LoongArch: KVM: Use CSR_CRMD_PLV in kvm_arch_vcpu_in_kernel()

The function reads LOONGARCH_CSR_CRMD but uses CSR_PRMD_PPLV to
extract the privilege level. While both masks have the same value
(0x3), CSR_CRMD_PLV is the semantically correct constant for CRMD.

Cc: stable@vger.kernel.org
Reviewed-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>