ARM: dts: wpcm450: Add FIU SPI controller node

Add the SPI controller (FIU, Flash Interface Unit) to the WPCM450
devicetree, according to the newly defined binding, as well as the SHM
(shared memory interface) syscon.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Link: https://lore.kernel.org/r/20221105185911.1547847-6-j.neuschaefer@gmx.net


Signed-off-by: Joel Stanley <joel@jms.id.au>