[PATCH] IB/mthca: use generic function instead of arbel_ version in mthca_free_region()

Use the generic key_to_hw_index() function instead of the Arbel-specific
version in mthca_free_region().

Signed-off-by: Guy German <guyg@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>