[U-Boot] efi_loader: initialize device path on alloc

[Alexander Graf]

> Since the backing memory for a new device path can contain stale
> data we have to make sure that we zero the buffer.  Otherwise some
> code paths that don't set all fields in a structure backed by this
> device path might contain unwanted stale data.
> 
> Signed-off-by: Patrick Wildt <patrick at blueri.se>
> Reviewed-by: Heinrich Schuchardt <xypron.glpk at gmx.de>

Thanks, applied to efi-next

Alex