IB/ehca: spin_lock_irqsave() takes an unsigned long

The flags argument to spin_lock_irqsave() should really be unsigned
long.  This will also help prevent some warnings when we change u64 to
unsigned long long.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Roland Dreier <rolandd@cisco.com>