USB: dwc3: drop dead hibernation code

USB: dwc3: drop dead hibernation code

The hibernation code is broken and has never been enabled in mainline
and should thus be dropped.

Specifically, the scratch buffer DMA mapping would have been leaked on
every suspend cycle since commit 51f5d49ad6f0 ("usb: dwc3: core:
simplify suspend/resume operations") if this feature was ever enabled.

The related error handling was also broken and could have resulted in
attempts to unmap never mapped buffers, etc.

This effectively revert commit 0ffcaf3798bf ("usb: dwc3: core: allocate
scratch buffers").

Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20230404072524.19014-6-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>