UPSTREAM: usb: dwc3: core: Add missing GHWPARAMS9 doc

Add missing documentation for struct dwc3_hwparams new field hwparams9
to avoid kernel doc build warning.

Fixes: 16710380 ("usb: dwc3: Capture new capability register GHWPARAMS9")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/f4c491f7614e623755fafe640b7e690e7c5634e2.1619471127.git.Thinh.Nguyen@synopsys.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 9cbc7eb1)
Bug: 187129171
Signed-off-by: Connor O'Brien <connoro@google.com>
Change-Id: Ib912141546f4b90770d2ad1cdc66bf4323bb5970