efi/libstub: Cast away type warning in use of max()

Avoid a type mismatch warning in max() by switching to max_t() and
providing the type explicitly.

Fixes: 3cb4a482 ("efi/libstub: fix efi_random_alloc() ...")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

drivers/firmware/efi/libstub/randomalloc.c

@@ -120,7 +120,7 @@ efi_status_t efi_random_alloc(unsigned long size,
 			continue;
 		}
 
-		target = round_up(max(md->phys_addr, alloc_min), align) + target_slot * align;
+		target = round_up(max_t(u64, md->phys_addr, alloc_min), align) + target_slot * align;
 		pages = size / EFI_PAGE_SIZE;
 
 		status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,