usb: xhci: remove unused variables from struct 'xhci_hcd'

Variables 'max_slots', 'max_ports', 'isoc_threshold' and 'event_ring_max'
are never set or used. Thus, remove them.

Signed-off-by: Niklas Neronin <niklas.neronin@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20240905143300.1959279-7-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Epicurius

drivers/usb/host/xhci.h

@@ -1500,13 +1500,9 @@ struct xhci_hcd {
 	/* packed release number */
 	u8		sbrn;
 	u16		hci_version;
-	u8		max_slots;
 	u16		max_interrupters;
-	u8		max_ports;
-	u8		isoc_threshold;
 	/* imod_interval in ns (I * 250ns) */
 	u32		imod_interval;
-	int		event_ring_max;
 	/* 4KB min, 128MB max */
 	int		page_size;
 	/* Valid values are 12 to 20, inclusive */