efi_loader: make pool allocations cacheline aligned

This avoids printf() spam about file reads (such as loading an image)
into unaligned buffers (and the associated memcpy()).  And generally
seems like a good idea.

Signed-off-by: Rob Clark <robdclark@gmail.com>
[agraf: use __aligned]
Signed-off-by: Alexander Graf <agraf@suse.de>