multilib_global: Fix PREFERRED_VERSION mapping for gcc-cross-canadian
Our multilib cross toolchains have <ml_prefix> as a prefix however we
only have a single gcc-cross-canadian for each arch and it is not
prefixed even in the multilib case. We can have two versions of
gcc-cross-canadian, 32 and 64 bit.
This fixes the multilib PREFERRED_VERSION mapping code so that
no prefix is added to the preferred version and therefore the
right versions of gcc-cross-canadian are used.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
