staging: most: aim-network: fix interrupt unsafe spinlocks

The networking AIM does not use the *_irqsave and *_irqrestore flavored
spinlock functions. The rx_completion callback, however, can be called
from an interrupt context.

This patch is needed to fix this problem.

Signed-off-by: Andrey Shvetsov <andrey.shvetsov@k2l.de>
Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>