Set DISTRO with ?=
Set DISTRO with ?=

Make way for Iota distro

Change-Id: Icc5b27c32d5c2f5386658e956a2d025767d3749d
Signed-off-by: Khem Raj <729d64b6f67515e258459a5f6d20ec88b2caf8df@gmail.com>

Angstrom-distribution/angstrom-manifest