xhci: dbc: Pass dbc pointer to endpoint init and exit functions.

xhci: dbc: Pass dbc pointer to endpoint init and exit functions.

struct xhci_hcd pointer is not needed for dbc endpoint init and exit,
it was only used to get to the dbc structure.
Pass the dbc pointer as a parameter to these functions instead.

No functional changes
This change helps decoupling xhci and DbC

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200723144530.9992-13-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>