UPSTREAM: usb: dwc2: host: use kmem cache to allocate descriptors

UPSTREAM: usb: dwc2: host: use kmem cache to allocate descriptors

Kmem caches help to get correct boundary for descriptor buffers
which need to be 512 bytes aligned for dwc2 controller.
Two kmem caches are needed for generic descriptors and for
hs isochronous descriptors which doesn't have same size.

Change-Id: Ic5af8b3871a32d51942aad35e0968ddbd803a73e
Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Gregory Herrero <gregory.herrero@intel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Huang, Tao <huangtao@rock-chips.com>
(cherry picked from commit 3b5fcc9ac2f4453a5609cc89ac7618b1b27ccb01)