Merge tag 'efi-2020-04-rc4-6' of https://gitlab.denx.de/u-boot/custodians/u-boot-efi

Pull request for UEFI sub-system for efi-2020-04-rc4 (6)

This series fixes:

* UEFI Python test for helloworld requires CONFIG_OF_CONTROL=y.
* int to pointer cast warning for cmd/efidebug.c
* memory reservation even if fdt node is disabled

Now that the Python test is fixed reintroduce the reverted patch for
vexpress_ca9x4 to enable EFI_LOADER and define the dtb file name.