USB: EHCI: prepare to make ehci-hcd a library module

USB: EHCI: prepare to make ehci-hcd a library module

This patch (as1624) prepares ehci-hcd for being split up into a core
library and separate platform driver modules.  A generic
ehci_hc_driver structure is created, containing all the "standard"
values, and a new mechanism is added whereby a driver module can
specify a set of overrides to those values.  In addition the
ehci_setup(), ehci_suspend(), and ehci_resume() routines need to be
EXPORTed for use by the drivers.

As a side effect of this change, a few routines no longer need to be
marked __maybe_unused.

Signed-off-by: Alan Stern <[email protected]>
CC: Felipe Balbi <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>