can: mcp25xxfd: mcp25xxfd_ring_free(): fix memory leak during cleanup

This loop doesn't free the first element of the array.  The "i > 0" has
to be changed to "i >= 0".

Fixes: 55e5b97f ("can: mcp25xxfd: add driver for Microchip MCP25xxFD SPI CAN")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20200923112752.GA1473821@mwanda


Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>