liquidio: Fix wrong return value in cn23xx_get_pf_num()

On an error exit path, a negative error code should be returned
instead of a positive return value.

Fixes: 0c45d7fe ("liquidio: fix use of pf in pass-through mode in a virtual machine")
Cc: Rick Farrington <ricardo.farrington@cavium.com>
Signed-off-by: NTianjia Zhang <tianjia.zhang@linux.alibaba.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/cavium/liquidio/cn23xx_pf_device.c

@@ -1167,7 +1167,7 @@ static int cn23xx_get_pf_num(struct octeon_device *oct)
 		oct->pf_num = ((fdl_bit >> CN23XX_PCIE_SRIOV_FDL_BIT_POS) &
 			       CN23XX_PCIE_SRIOV_FDL_MASK);
 	} else {
-		ret = EINVAL;
+		ret = -EINVAL;
 
 		/* Under some virtual environments, extended PCI regs are
 		 * inaccessible, in which case the above read will have failed.