spi: lantiq: Add SMP support

Existing driver supports only single core SoC. New multicore platforms uses
the same driver/IP so SMP support is required. This patch adds multicore
support in the driver.

Signed-off-by: Dilip Kota <eswara.kota@linux.intel.com>
Link: https://lore.kernel.org/r/d6663296b41f102c582fda08e71f62b72ca05d5d.1594957019.git.eswara.kota@linux.intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>