spi: aspeed: Adjust direct mapping to device size

spi: aspeed: Adjust direct mapping to device size

The segment registers of the FMC/SPI controllers provide a way to
configure the mapping window of the flash device contents on the AHB
bus. Adjust this window to the size of the spi-mem mapping.

Things get more complex with multiple devices. The driver needs to
also adjust the window of the next device to make sure that there is
no overlap, even if there is no available device. The proposal below
is not perfect but it is covering all the cases we have seen on
different boards with one and two devices on the same bus.

Reviewed-by: Joel Stanley <joel@jms.id.au>
Tested-by: Joel Stanley <joel@jms.id.au>
Tested-by: Tao Ren <rentao.bupt@gmail.com>
Tested-by: Jae Hyun Yoo <quic_jaehyoo@quicinc.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Link: https://lore.kernel.org/r/20220509175616.1089346-6-clg@kaod.org
Signed-off-by: Mark Brown <broonie@kernel.org>