efi: Fix to use null handle to create new handle for efi_fmp_raw

When running the efidebug capsule disk-update command, the efi_fmp_raw
protocol installation fails with 2 (EFI_INVALID_PARAMETER) as below.
This is because the code passes efi_root instead of the handle local var.

=> efidebug capsule disk-update
EFI: Call: efi_install_multiple_protocol_interfaces( &handle, &efi_guid_firmware_management_protocol, &efi_fmp_fit, NULL)
  EFI: Entry efi_install_multiple_protocol_interfaces(00000000fbaf5988)
    EFI: Call: efi_install_protocol_interface( handle, protocol, EFI_NATIVE_INTERFACE, protocol_interface)
      EFI: Entry efi_install_protocol_interface(00000000fbaf5988, 86c77a67-0b97-4633-a187-49104d0685c7, 0, 00000000fbfa6ee8)
        EFI: new handle 00000000fbb37520
      EFI: Exit: efi_install_protocol_interface: 0
    EFI: 0 returned by efi_install_protocol_interface( handle, protocol, EFI_NATIVE_INTERFACE, protocol_interface)
  EFI: Exit: efi_install_multiple_protocol_interfaces: 0
EFI: 0 returned by efi_install_multiple_protocol_interfaces( &handle, &efi_guid_firmware_management_protocol, &efi_fmp_fit, NULL)
EFI: Call: efi_install_multiple_protocol_interfaces( &efi_root, &efi_guid_firmware_management_protocol, &efi_fmp_raw, NULL)
  EFI: Entry efi_install_multiple_protocol_interfaces(00000000fbfec648)
    EFI: Call: efi_install_protocol_interface( handle, protocol, EFI_NATIVE_INTERFACE, protocol_interface)
      EFI: Entry efi_install_protocol_interface(00000000fbfec648, 86c77a67-0b97-4633-a187-49104d0685c7, 0, 00000000fbfa6f18)
        EFI: handle 00000000fbaf8520
      EFI: Exit: efi_install_protocol_interface: 2
    EFI: 2 returned by efi_install_protocol_interface( handle, protocol, EFI_NATIVE_INTERFACE, protocol_interface)
  EFI: Exit: efi_install_multiple_protocol_interfaces: 2
EFI: 2 returned by efi_install_multiple_protocol_interfaces( &efi_root, &efi_guid_firmware_management_protocol, &efi_fmp_raw, NULL)
Command failed, result=1

To fix this issue, pass the handle local var which is set NULL right
before installing efi_fmp_raw as same as the installing efi_fmp_fit.
(In both cases, the local reference to the handle will be just discarded)

Signed-off-by: Masami Hiramatsu <masami.hiramatsu@linaro.org>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>