mem: Fix missing delete of packet in DRAM access
mem: Fix missing delete of packet in DRAM access

This patch fixes a memory leak caused by not deleting packets that
require no response.

andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin