The isr supports shared operation, so register it with the IRQF_SHARED
flag to indicate this.

This patch also removes the IRQF_DISABLED flag.  This driver doesn't
need it, and IRQF_DISABLED isn't guaranteed when using shared interrupts.
Signed-off-by: NSteve Glendinning <steve.glendinning@smsc.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>