Fix: GetDevlinkDeviceParam to handle edge-cases correctly

[ykulazhenkov]

On some kernels GetDevlinkDeviceParam may return empty values for some kernel parameters. The netlink library is able to handle this, but the code in GetDevlinkDeviceParam function may panic if unexpected value received.
Add extra checks to avoid panics.

The problem was discovered on an old kernel (5.15.0-25-generic) for Ubuntu 22.04.
The parameter has no value:

devlink dev param show pci/0000:08:00.0 name flow_steering_mode
pci/0000:08:00.0:
  name flow_steering_mode type driver-specific
    values:

segfault happens when trying to set the value

devlink dev param set pci/0000:08:00.0 name flow_steering_mode value smfs  cmode runtime
Segmentation fault (core dumped)

In the recent kernels everything works as expected. This change is primarily intended to enhance the operator's robustness, rather than to address any current issues.

[github-actions]

Thanks for your PR,
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  Best regards.

[coveralls]

Pull Request Test Coverage Report for Build 10998783450

Details

• 8 of 20 (40.0%) changed or added relevant lines in 2 files are covered.
• 2 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.008%) to 45.042%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/host/internal/sriov/sriov.go	0	5	0.0%
pkg/host/internal/network/network.go	8	15	53.33%

Files with Coverage Reduction	New Missed Lines	%
controllers/drain_controller.go	1	68.06%
pkg/host/internal/network/network.go	1	56.11%

Totals
Change from base Build 10979758277:	0.008%
Covered Lines:	6632
Relevant Lines:	14724

---

💛 - Coveralls

[adrianchiris]

LGTM !

[ykulazhenkov]

@zeeke @SchSeba Can you check this one? Thanks

[zeeke]

LGTM