kconfig: Define the IRQ priorities for CAVS & DW ICTL

CAVS_ICTL_0_IRQ_PRI to CAVS_ICTL_3_IRQ_PRI and DW_ICTL_IRQ_PRI
are now defined in Kconfig. This addresses the issue #7811.

This was not throwing up any compilation error earlier as the IRQ
priorities are all hardwired in Xtensa and hence are unconfigurable.
They are dummy for Xtensa arch but may be applicable if used in some
other arch.

Signed-off-by: Rajavardhan Gundi <rajavardhan.gundi@intel.com>