usb: xhci: remove '0' write to write-1-to-clear register

usb: xhci: remove '0' write to write-1-to-clear register

xHCI specification 1.2, section 5.5.2.1.
Interrupt Pending bit is RW1C (Write-1-to-clear), which means that
writing '0' to is has no effect and is removed.

The Interrupt Pending (IP) bit is cleared at the start of interrupt
handling; xhci_clear_interrupt_pending(). This could theoretically
cause a new interrupt to be issued before the xhci driver reaches
the interrupter disable functions.
To address this, the IP bit is read after Interrupt Enable is
disabled, and a debug message is issued if the IP bit is still set.

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/20250515135621.335595-18-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>