LoongArch: KVM: Use existing macro about interrupt bit mask

LoongArch: KVM: Use existing macro about interrupt bit mask

With interrupt post, register CSR.GINTC and CSR.ESTAT is used, and
CSR.ESTAT is used for percpu interrupt injection and CSR.GINTC is for
external hardware interrupt injection.

Here use existing macro about interrupt bit of register CSR.GINTC and
CSR.ESTAT, rather than hard coded constant value.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>