usb: xhci-mem: use passed in GFP flags instead of GFP_KERNEL

We normally use the passed in gfp flags for allocations, it's just these
two which were missed.

Fixes: 22d45f01 ("usb/xhci: replace pci_*_consistent() with dma_*_coherent()")
Cc: Mathias Nyman <mathias.nyman@intel.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>