IB/mlx4: avoid a -Wmaybe-uninitialize warning

There is an old warning about mlx4_SW2HW_EQ_wrapper on x86:

ethernet/mellanox/mlx4/resource_tracker.c: In function ‘mlx4_SW2HW_EQ_wrapper’:
ethernet/mellanox/mlx4/resource_tracker.c:3071:10: error: ‘eq’ may be used uninitialized in this function [-Werror=maybe-uninitialized]

The problem here is that gcc won't track the state of the variable
across a spin_unlock. Moving the assignment out of the lock is
safe here and avoids the warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>