isci: kill some long macros

Delete some macros that are longer to type than the open coded operation
that they perform.

scic_sds_phy_get_base_state_machine
scic_sds_phy_get_starting_substate_machine
scic_sds_port_get_base_state_machine
scic_sds_port_get_ready_substate_machine
scic_sds_remote_device_get_base_state_machine
scic_sds_remote_device_get_ready_substate_machine
scic_sds_remote_node_context_set_remote_node_index
scic_sds_controller_get_base_state_machine

Also performs some collateral cleanups like killing casts that assume
structure member ordering, and consolidating a lot of duplicated default
handler code (the primary callers of the *_get_base_state_machine macros) via
a helper.

Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>