EFI: don't use alias attribute for compat hypercall stubs

Recent Clang objects to types differing between alias and aliasee. Accept
the unnecessary overhead and make the two compat stubs real functions.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>

xen/common/efi/common-stub.c

@@ -27,10 +27,14 @@ int efi_runtime_call(struct xenpf_efi_runtime_call *op)
 
 #ifdef CONFIG_COMPAT
 
-int efi_compat_get_info(uint32_t idx, union compat_pf_efi_info *)
-    __attribute__((__alias__("efi_get_info")));
+int efi_compat_get_info(uint32_t idx, union compat_pf_efi_info *info)
+{
+    return -ENOSYS;
+}
 
-int efi_compat_runtime_call(struct compat_pf_efi_runtime_call *)
-    __attribute__((__alias__("efi_runtime_call")));
+int efi_compat_runtime_call(struct compat_pf_efi_runtime_call *op)
+{
+    return -ENOSYS;
+}
 
 #endif