imx-base.inc: Change default Linux kernel to linux-fslc-imx
The linux-imx does not offer fixes for security issues as well as new
toolchain tooling, as we maintain an alternative Linux flavor it make
sense to use it.
The kernel can still to be overridden on the machine or
distro definition, so preserving the flexibility.
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Change-Id: I2378881cf9951f3dd85f758edf19af48185a50e8
(cherry picked from commit
14d9e269562d7a6376ed55411783ef4115e319c5)
