can: gs_usb: remove dma allocations

can: gs_usb: remove dma allocations

DMA allocated buffers are a precious resource. If there is no need for
DMA allocations, then it might be worth to use non-dma allocated
buffers.

After testing the gs_usb driver with and without DMA allocation, there
does not seem to be a significant change in latency or CPU utilization
either way. Therefore, DMA allocation is not necessary and removed.

Internal buffers used within urbs were managed and freed manually.
These buffers are no longer needed to be managed by the driver. The
URB_FREE_BUFFER flag, allows for the buffers in question to be
automatically freed.

Co-developed-by: Rhett Aultman <rhett.aultman@samsara.com>
Signed-off-by: Rhett Aultman <rhett.aultman@samsara.com>
Signed-off-by: Vasanth Sadhasivan <vasanth.sadhasivan@samsara.com>
Link: https://lore.kernel.org/all/20220920154724.861093-2-rhett.aultman@samsara.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>