efi_loader: export efi_convert_pointer()

We need ConvertPointer() to adjust pointers when implementing  runtime
services within U-Boot.

After ExitBootServices() gd is not available anymore. So we should not use
EFI_ENTRY() and EFI_EXIT().

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/include/efi_loader.h b/include/efi_loader.h
index ceabbaa..be6cede 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -397,6 +397,9 @@
 efi_status_t efi_initialize_system_table(void);
 /* efi_runtime_detach() - detach unimplemented runtime functions */
 void efi_runtime_detach(void);
+/* efi_convert_pointer() - convert pointer to virtual address */
+efi_status_t EFIAPI efi_convert_pointer(efi_uintn_t debug_disposition,
+					void **address);
 /* Called by bootefi to make console interface available */
 efi_status_t efi_console_register(void);
 /* Called by bootefi to make all disk storage accessible as EFI objects */