mosys: Support sku-id as an identifier for ARM

CQ-DEPEND=CL:1271458, CL:*693332, CL:*697228
TEST=start tryjobs with CL:*693332, CL:*697228, CL:1271458,
CL:1274766, and CL:1274767 for scarlet, cheza, nautilus, fizz,
nami, all builds succeed.
TEST=manaully verify 'mosys platform id' works on dru, cheza,
and nautilus with trybot images

Change-Id: I82bca0b634dd17fa3e3d700198672fadb4e00644
Commit-Ready: Philip Chen <>
Tested-by: Philip Chen <>
Reviewed-by: Aaron Durbin <>
5 files changed