insane.bbclass: remove skipping of cross-compiled packages

After commit cd25e554 ("insane: use HOST_ variables, not TARGET_ to
determine the cross system"), this check is no longer necessary. The
introduction of HOST_ variables ensures architecture compatibility is
correctly checked.

Signed-off-by: Emil Kronborg <emil.kronborg@protonmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
(cherry picked from commit 6e1ddeb0)
Signed-off-by: Steve Sakoman <steve@sakoman.com>