fm10k: return proper error code when pci_enable_msix_range fails

The pci_enable_msix_range() function returns a positive value of the
number of allocated vectors if it succeeds. On failure it returns
a negative error code. Return this code properly so that the error
message printed by the driver will show the actual error code instead of
being masked by -ENOMEM.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>