qlcnic: check pci_reset_function result

Static code analyzer complains to unchecked return value.
The result of pci_reset_function() is unchecked.
Despite, the issue is on the FLR supported code path and in that
case reset can be done with pcie_flr(), the patch uses less invasive
approach by adding the result check of pci_reset_function().

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 7e2cf4fe ("qlcnic: change driver hardware interface mechanism")
Signed-off-by: Denis Plotnikov <den-plotnikov@yandex-team.ru>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>