16k: Move BoardConfig-shusky-common.mk to device/google/zuma/BoardConfig-16k-common.mk

The makefile logic in this file is identical to the logic required for
akita-trunk_staging-userdebug. Hence, this logic is moved to
device/google/zuma/BoardConfig-16k-common.mk to avoid duplicating the
file for akita.

Bug: 370842132
Bug: 349877551
Test: Built and booted up `aosp_shiba` and and `aosp_shiba-pgagnostic` targets
Flag: EXEMPT bugfix
Change-Id: I80cb3e9f4c4a1609ca668af554d930edb3b4c5a0
Merged-In: I80cb3e9f4c4a1609ca668af554d930edb3b4c5a0
3 files changed