Both variables were used (with the same value) interchangeably
throughout CMake files and per the discussion in GH issue,
ZEPHYR_BASE is preferred.
Also add a comment with explanation of one vs. the other.
Tested by building hello_world for several boards ensuring no errors.
Fixes#7173.
Signed-off-by: Alex Tereschenko <alext.mkrs@gmail.com>
Added support for the HiFive1 board from SiFive
Signed-off-by: Tomasz Michalak <tmichalak@antmicro.com>
Signed-off-by: Karol Gugala <kgugala@antmicro.com>
Signed-off-by: Tomasz Jurtsch <tjurtsch@antmicro.com>