DISTRO should be set to "nodistro" for distro-less configurations since
empty string results in empty items ending up in OVERRIDES leading to
unexpected behaviour with FILESPATH.

(From OE-Core rev: 25436b6813b6245faeb981cf93a0c32b871dd8d3)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>