hostmem: drop error variable from host_memory_backend_get_memory()

Unused, so let's remove it.

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20180619134141.29478-8-david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/backends/hostmem.c b/backends/hostmem.c
index 3627e61..4908946 100644
--- a/backends/hostmem.c
+++ b/backends/hostmem.c
@@ -247,8 +247,7 @@
     return memory_region_size(&backend->mr) != 0;
 }
 
-MemoryRegion *
-host_memory_backend_get_memory(HostMemoryBackend *backend, Error **errp)
+MemoryRegion *host_memory_backend_get_memory(HostMemoryBackend *backend)
 {
     return host_memory_backend_mr_inited(backend) ? &backend->mr : NULL;
 }