usb: xhci: refactor xhci_set_cmd_ring_deq()

usb: xhci: refactor xhci_set_cmd_ring_deq()

Refactor xhci_set_cmd_ring_deq() making the code more understandable by
using more descriptive constants and separating operations logically.

- Remove 'CMD_RING_RSVD_BITS' the macro is misleading, the reserved bits
  are 5:4, yet the mask is for bits 5:0.
- Introduce masks 'CMD_RING_PTR_MASK' and 'CMD_RING_CYCLE' to clearly
  define the bits for the Command Ring pointer and Command Ring Cycle.
- Simplifying the process of setting the command ring address by separating
  the DMA address calculation and the Command Ring Control register (crcr)
  updates.
- Remove the "// " prefix from trace messages, as it is unnecessary and
  distracting.

Note: In the current implementation, the cycle bit is not cleared before
applying the OR operation. Although this hasn't caused issues so far
because the bit is '0' before reaching this function, the bit is now
cleared before being set to prevent potential future problems and simplify
the process.

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/20250515135621.335595-7-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>