ethtool: fail closed if we can't get max channel used in indirection tables

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/ethtool/channels.c",
                        "net/ethtool/common.c",
                        "net/ethtool/common.h",
                        "net/ethtool/ioctl.c"
                    ],
                    "versions": [
                        {
                            "version": "d4ab4286276fcd6c155bafdf4422b712068d2516",
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                        }
                    ]
                }

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/ethtool/channels.c",
                        "net/ethtool/common.c",
                        "net/ethtool/common.h",
                        "net/ethtool/ioctl.c"
                    ],
                    "versions": [
                        {
                            "version": "4.6",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "4.6",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.1.191",
                            "lessThanOrEqual": "6.1.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.6.160",
                            "lessThanOrEqual": "6.6.*",
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                            "versionType": "semver"
                        },
                        {
                            "version": "6.10.10",
                            "lessThanOrEqual": "6.10.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.11",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }