xhci: Fix USB ports for Dell Inspiron 5775

The Dell Inspiron 5775 is a Raven Ridge. The Enable Slot command timed
out when a USB device gets plugged:
[ 212.156326] xhci_hcd 0000:03:00.3: Error while assigning device slot ID
[ 212.156340] xhci_hcd 0000:03:00.3: Max number of devices this xHCI host supports is 64.
[ 212.156348] usb usb2-port3: couldn't allocate usb_device

AMD suggests that a delay before xHC suspends can fix the issue.

I can confirm it fixes the issue, so use the suspend delay quirk for
Raven Ridge's xHC.

Cc: stable@vger.kernel.org
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>