[U-Boot] [U-Boot, v2] efi_loader: initialise partition_signature memory

[Alexander Graf]

> Zero partition_signature in the efi_device_path_hard_drive_path
> structure when signature_type is 0 (no signature) as required by the
> UEFI specification.
> 
> This is required so that efi_dp_match() will work as expected
> when doing memcmp() comparisons.  Previously uninitialised memory
> would cause it not match nodes when it should have when the signature
> type was not GUID.
> 
> Corrects a problem where the loaded image protocol would not return a
> device path with MEDIA_DEVICE causing the OpenBSD bootloader to fail
> on rpi_3 and other targets.
> 
> v2: Also handle signature_type 1 (MBR) as described in the specification
> 
> Signed-off-by: Jonathan Gray <jsg at jsg.id.au>
> Tested-by: Artturi Alm <artturi.alm at gmail.com>

Thanks, applied to efi-next

Alex