armv8: layerscape: use memalign() to allocate spintable code

Don't use efi_allocate_pages(). The allocated memory isn't carved out of
the lmb allocations. The memory might then be allocated twice.
Particulary, this might happened with the fdt_high/initrd_high feature
which will relocate the fdt/ramdisk. This might then overlap with the
spin table.

Instead use memalign() which allocates on memory on the heap which is
correctly carved out by lmb.

Please note, that the memory is later reserved in the device tree as
well as in the EFI memory map in ft_fixup_cpu() (in
arch/arm/cpu/armv8/fsl-layerscape/fdt.c).

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>