driver: ssp: remove use of out-of-tree CONFIG_INTEL_MN

The SSP driver has odd dependency to outside definition of
CONFIG_INTEL_NM. This is in practise tied to SSP hardware
version and always enabled for SSP block version 1.0.

Use the new SSP_IP_VER define to replace the CONFIG_INTEL_MN
preprocssor checks. Also modify the board test case to
remove the obsolete config setting.

Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>