tfa-layerscape: build fiptool again

tfa-layerscape: build fiptool again

The ls-ddr-phy package needs fiptool options that are not
available via the version from arm-trusted-firmware-tools.
This breaks build for layerscape with the recently added LX2160a:

  create: unrecognized option '--ddr-immem-udimm-1d'

Use the tfa-layerscape variant again for now, but rename it to
fiptool-layerscape to indicate that it's a specific variant.

This reverts 84bc7d31e0a8 ("tfa-layerscape: don't build fiptool").

Fixes: f59d7aab2a37 ("layerscape: add ddr-phy package")
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>