gcc/go: Drop crosssdk suffix from virtual provides to improve dependency handling

gcc/go: Drop crosssdk suffix from virtual provides to improve dependency handling

There is little point in having "crosssdk" suffex added to the virtual provider within
gcc/go since the TARGET_PREFIX or SDK_PREFIX already encapsulates this. Remove it
allowing some of the special case overriding to be removed.

This also allows removal of some of the MLPREFIX usage since again, the triplet
also covers this.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>