can: peak/pci: fix potential bug when probe() fails

PCI/PCIe drivers for PEAK-System CAN/CAN-FD interfaces do some access to the
PCI config during probing. In case one of these accesses fails, a POSITIVE
PCIBIOS_xxx error code is returned back. This POSITIVE error code MUST be
converted into a NEGATIVE errno for the probe() function to indicate it
failed. Using the pcibios_err_to_errno() function, we make sure that the
return code will always be negative.

Signed-off-by: Stephane Grosjean <s.grosjean@peak-system.com>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>