aoc: usb: xhci: fix argument errors for xhci decode functions

xhci decode function signature changed by upstream CL in main kernel.

Removes static char buffer usage in the following decode functions:
    xhci_decode_ctrl_ctx()
    xhci_decode_slot_context()
    xhci_decode_usbsts()
    xhci_decode_doorbell()
    xhci_decode_ep_context()

Caller must provide a buffer to use.

Relevant CLs:
for drivers/usb/host/xhci.h in main kernel
3f7f1baf7045c6a418d5858de23e9f5c6c58d5ff

for usb/xhci_hooks_impl_whi.c
acdd6008

Bug: 199698959
Bug: 204322624
Test: build pass
Signed-off-by: Roger Liao <rogerliao@google.com>
Change-Id: I47f7fe21ead861a962cb58cdebd5fa4812c8dbbc