Merge "db845c.mk: set DB845C_KERNEL_DIR to use environment when specified" am: fe771fcdfb am: 2ae5a2a2e6 am: 1773525b62 am: 9368804964 am: 56b45b2503

Original change: https://android-review.googlesource.com/c/device/linaro/dragonboard/+/1462043

Change-Id: I1d5682fdd83cc2a2880afdd30136be4ec99d1312