ath5k: Don't fiddle with MSI on suspend/resume.

Commit 256b152b005e319f985f50f2a910a75ba0def74f (ath5k: don't enable
MSI, we cannot handle it yet) has removed msi support, but overlooked
the suspend/resume code. This patch completes msi removal.

I don't consider this patch copyrightable, and thus put it into the
public domain. The result is of course a base.c file dual-licensed under
3-clause-BSD and GPL.

Signed-off-by: Michael Karcher <kernel@mkarcher.dialup.fu-berlin.de>
Acked-by: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>