spi: bcmbca-hsspi: Add driver for newer HSSPI controller

spi: bcmbca-hsspi: Add driver for newer HSSPI controller

The newer BCMBCA SoCs such as BCM6756, BCM4912 and BCM6855 include an
updated SPI controller that add the capability to allow the driver to
control chip select explicitly. Driver can control and keep cs low
between the transfers natively. Hence the dummy cs workaround or prepend
mode found in the bcm63xx-hsspi driver are no longer needed and this new
driver is much cleaner.

Signed-off-by: William Zhang <william.zhang@broadcom.com>
Link: https://lore.kernel.org/r/20230209200246.141520-15-william.zhang@broadcom.com
Signed-off-by: Mark Brown <broonie@kernel.org>