LoongArch: KVM: Fix typo issue about GCFG feature detection

This is typo issue and misusage about GCFG feature macro. The code
is wrong, only that it does not cause obvious problem since GCFG is
set again on vCPU context switch.

Fixes: 0d0df3c9 ("LoongArch: KVM: Implement kvm hardware enable, disable interface")
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>