imx-base.inc: Use ??= for PREFERRED_VERSION

The variable values set in meta-freescale with a default value, i.e.
with ?=, can be overridden just once by a user, with =.

Change the PREFERRED_VERSION settings to a weak default value, i.e.
with ??=, so users of meta-freescale are not so limited. When a
variable value is set with a weak default value, the variable can be
overridden by any successively higher priority layer with ??=.

Signed-off-by: Tom Hochstein <tom.hochstein@nxp.com>

0 files changed, 0 insertions, 0 deletions