arm: mvebu: Add SPI driver model support

This patch enables the DM support for the SPI driver and the
SPI NOR flash chips. Some MVEBU boards boot from SPI NOR, so
adding the aliases and enabling CONFIG_DM_SEQ_ALIAS is needed
here.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Luka Perkov <luka.perkov@sartura.hr>
Cc: Dirk Eibach <dirk.eibach@gdsys.cc>
Cc: Simon Glass <sjg@chromium.org>