efi_selftest: illegal cast to pointer in initrddump

On 32bit systems u64 cannot directly be cast to void *.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/lib/efi_selftest/initrddump.c b/lib/efi_selftest/initrddump.c
index c23a05c..325951b 100644
--- a/lib/efi_selftest/initrddump.c
+++ b/lib/efi_selftest/initrddump.c
@@ -272,7 +272,7 @@
 		error(L"Out of memory\r\n");
 		return ret;
 	}
-	*initrd = (void *)buffer;
+	*initrd = (void *)(uintptr_t)buffer;
 	ret = load_file2_prot->load_file(load_file2_prot, dp, false,
 					 initrd_size, *initrd);
 	if (ret != EFI_SUCCESS) {