bmcsetup: revert previous meaning of bmcport for Dell servers

[kcgthb]

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This PR is a proposal to re-align the meaning of ipmi.bmcport for Dell servers.

The PR is to fix issue #7316

The modification include

Change bmcsetup to make sure that bmcport=0 sets the iDRAC NIC on Dell servers as shared, and bmcport=1 configures it to use the dedicated interface, as documented in the ipmi table doc.

[kcgthb]

It would be great if this PR could be reviewed, and eventually merged. Thanks!

[samveen]

@gurevichmark @besawn for your kind attention.

[kcgthb]

I also removed the dependency on ipmitool delloem and used IPMI raw commands instead, to make it more robust across Dell server generations, and less dependent on specific ipmitool versions.