multilib_global.bbclass: fix setting preferred version for canadian recipes
Currently the TRANSLATED_TARGET_ARCH is not changed when trying
to set preferred version for canadian recipes.
e.g.
```
bitbake core-image-minimal -c populate_sdk -e > env
grep ^PREFERRED_VERSION_gcc-cross-canadian env
```
The result is:
"""
PREFERRED_VERSION_gcc-cross-canadian-x86-64="11.%"
"""
We need to explictly change DEFAULTTUNE to ensure TRANSLATED_TARGET_ARCH is
changed when trying to set the preferred version for multilib version of
the canadian recipes.
e.g.
```
bitbake core-image-minimal -c populate_sdk -e > env
grep ^PREFERRED_VERSION_gcc-cross-canadian env
```
The result is:
"""
PREFERRED_VERSION_gcc-cross-canadian-i686="11.%"
PREFERRED_VERSION_gcc-cross-canadian-x86-64="11.%"
"""
Signed-off-by: Chen Qi <Qi.Chen@windriver.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
