[PATCH] x86_64/i386 irq: Fix !CONFIG_SMP compilation

When removing set_native_irq I missed the fact that it was
called in a couple of places that were compiled even when
SMP support is disabled.  And since the irq_desc[].affinity
field only exists in SMP things broke.

Thanks to Simon Arlott <simon@arlott.org> for spotting this.

There are a couple of ways to fix this but the simplest one
is to just remove the assignments.  The affinity field is only
used to display a value to the user, and nothing on either i386
or x86_64 reads it or depends on it being any particlua value,
so skipping the assignment is safe.  The assignment that
is being removed is just for the initial affinity value before
the user explicitly sets it.  The irq_desc array initializes
this field to CPU_MASK_ALL so the field is initialized to
a reasonable value in the SMP case without being set.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>