package.bbclass: fix strip and split logic

package.bbclass: fix strip and split logic

In order for strip and split to work together, we need to populate the
data structors if either split OR strip are not inhibited.

Original behaviour:

INHIBIT_PACKAGE_STRIP: no strip, no debug split
INHIBIT_PACKAGE_DEBUG_SPLIT: strip, no split

Behaviour after this patch:

INHIBIT_PACKAGE_STRIP: no strip, debug split
INHIBIT_PACKAGE_DEBUG_SPLIT: strip, no split
BOTH: no strip, no split, DNP data structures

Signed-off-by: Stephano Cetola <stephano.cetola@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>