Current count, from CMTS initialization, of unicast granted
minislots on the upstream logical channel, regardless of burst
type. Unicast granted minislots are those in which the CMTS
assigned bandwidth to any unicast SID on the logical channel.
This is the 32 bit version of docsIfCmtsUpChnlCtrExtUcastGrantedMslots,
and is included for back compatibility with SNMPv1 managers.
Support for this object is mandatory.