xhci: dbgtty: Pass dbc pointer when registering a dbctty device

xhci: dbgtty: Pass dbc pointer when registering a dbctty device

Pass dbc pointer to the xhci_dbc_tty_register_device() and
xhci_dbc_tty_unregister_device() functions instead of xhci_hcd pointer

These functions don't need a xhci_hcd pointer anymore, only use case was
the xhci_err() function, which is now changed to a dev_err() 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/20200723144530.9992-16-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>