intel_adsp: do not use SOC_TOOLCHAIN_NAME for include path

SOC_TOOLCHAIN_NAME was used instead of the SoC name for setting include
path, so all SoCs were using the same path. Originally this was relying
on SoC (before hwmv2), so reverting back to using the SoC name instead
and renaming directories as well.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>