sstate.bbclass: Move crosssdk before cross to ensure correct variables are set

sstate.bbclass: Move crosssdk before cross to ensure correct variables are set

There was a bug showing up where the crosssdk recipes were being installed as machine
specific in the sstate-control directory. This turned out to be due to the architecture
fields used by sstate being set incorrectly. The problem is that the crosssdk inherits
the cross class. It therefore needs to be listed in this if statement block before
the cross check, not after.

This should resolve some package architecture issue of crosssdk sstate files.

(From OE-Core rev: 79fe28e6033273f9632ca7549d1599d3fd1463ef)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>