usb: xhci: simplify handling of Structural Parameters 1 values

usb: xhci: simplify handling of Structural Parameters 1 values

The 32-bit read-only HCSPARAMS1 register contains the following fields:
 Bits  7:0   - Number of Device Slots (MaxSlots)
 Bits 18:8   - Number of Interrupters (MaxIntrs)
 Bits 23:19  - Reserved
 Bits 31:24  - Number of Ports (MaxPorts)

Since the register value is constant for the lifetime of the controller,
it is cached in 'xhci->hcs_params1'. However, platform drivers may
override the number of interrupters through a separate variable,
'xhci->max_interrupters', leaving only the maximum slots and ports values
still derived from the cached register.

To simplify the code and improve readability, replace 'xhci->hcs_params1'
with two dedicated 'u8' fields: 'xhci->max_slots' and 'xhci->max_ports'.
These values are initialized once and used directly instead of calling
'HCS_MAX_SLOTS()' and 'HCS_MAX_PORTS()' macros.

This change reduces code clutter without increasing memory usage.

Signed-off-by: Niklas Neronin <niklas.neronin@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://patch.msgid.link/20251119142417.2820519-16-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>