After review by the WDC engineers, improve how we pull down the
so-called 'e6' logs. The 'c6' logs are obsolete and support for them
has been removed because FreeBSD needed to pull them in chunks, which
is incompatible with the 0xc6 opcode implementation. Rather than leave
the code in place that produces bad log pulls, remove it.
wdc cap-diag Capture diagnostic data from drive
wdc drive-log Capture drive history data from drive
wdc get-crash-dump Retrieve firmware crash dump from drive