Opaque virtual address type

This ensures that conversions and arithmetic on virtual addresses are
explicit and not accidental due to it being a primitive integer.

Change-Id: I94dd8e82e065757ae448d98be0cb89eaa1f6542d
diff --git a/inc/api.h b/inc/api.h
index 851c2da..1db9ca8 100644
--- a/inc/api.h
+++ b/inc/api.h
@@ -16,7 +16,7 @@
 int32_t api_vcpu_get_count(uint32_t vm_idx);
 int32_t api_vcpu_run(uint32_t vm_idx, uint32_t vcpu_idx, struct vcpu **next);
 struct vcpu *api_wait_for_interrupt(void);
-int32_t api_vm_configure(paddr_t send, paddr_t recv);
+int32_t api_vm_configure(ipaddr_t send, ipaddr_t recv);
 
 int32_t api_rpc_request(uint32_t vm_idx, size_t size);
 int32_t api_rpc_read_request(bool block, struct vcpu **next);