CleanSpec.mk: Remove HOST_OUT_release

CleanSpec.mk: Remove HOST_OUT_release

This is a forward port of a patch from the AOSP/master tree:
https://android.googlesource.com/platform/external/mesa3d/+/bd633f11de0c6ac1ed333a28344c74fd9898df9e%5E%21/

Which replaces HOST_OUT_release with HOST_OUT

As per Dan's explanation, the current code was incorrect to use
$(HOST_OUT_release) as $(HOST_OUT) will be set properly for
whether the current build that's being cleaned during
incrementals is using host debug or release builds.

Additionally Dan noted it was incredibly uncommon to use a debug
host build, as there was never a shortcut and one had to set an
environment variable manually. Thus it was rarely if ever tested.

Change-Id: I7972c0a50fa3520dcfa962d6dd7e602bfe22368d
Cc: Rob Herring <rob.herring@linaro.org>
Cc: Alistair Strachan <astrachan@google.com>
Cc: Marissa Wall <marissaw@google.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Emil Velikov <emil.l.velikov@gmail.com>
Cc: Rob Clark <robdclark@gmail.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Rob Herring <robh@kernel.org>