DC5 and DC6 counter register tells about residency of DC5 and DC6.
Added the same in debugfs file.

v2 : Remove csr_version check.
     Added generic check regarding DC counters for  Gen9 onwards. (Rodrigo)
v3 : Simplified gen checks. (Chris)
v4 : Simplified "if" ladder for multiple gens.
v5 : Removed unnecessary comment.
Signed-off-by: Jyoti Yadav <jyoti.r.yadav@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1538762926-4880-1-git-send-email-jyoti.r.yadav@intel.com