PCI: Extend isolated function probing to LoongArch

Like s390 and the jailhouse hypervisor, LoongArch's PCI architecture allows
passing isolated PCI functions to a guest OS instance. So it is possible
that there is a multi-function device without function 0 for the host or
guest.

Allow probing such functions by adding a IS_ENABLED(CONFIG_LOONGARCH) case
in the hypervisor_isolated_pci_functions() helper.

This is similar to commit 189c6c33ff42 ("PCI: Extend isolated function
probing to s390").

Signed-off-by: Huacai Chen <[e-mail]>
Signed-off-by: Bjorn Helgaas <[e-mail]>
Cc: [e-mail]
Link: https://patch.msgid.link/[e-mail]

include/linux/hypervisor.h

···
 	if (IS_ENABLED(CONFIG_S390))
 		return true;
 
+	if (IS_ENABLED(CONFIG_LOONGARCH))
+		return true;
+
 	return jailhouse_paravirt();
 }