x86/efi: efi_unmap_boot_services: fix calculation of ranges_to_free size

x86/efi: efi_unmap_boot_services: fix calculation of ranges_to_free size

ranges_to_free array should have enough room to store the entire EFI
memmap plus an extra element for NULL entry.
The calculation of this array size wrongly adds 1 to the overall size
instead of adding 1 to the number of elements.

Add parentheses to properly size the array.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Fixes: a4b0bf6a40f3 ("x86/efi: defer freeing of boot services memory")
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>