Indicates whether extended buffer-to-buffer credit
feature can be enabled on a given interface.
'true' : capable of changing the extended buffer-to-buffer
credits on the interface. The user can configure the
object fcIfAdminRxBbCreditExtended on this interface.
'false' : not capable of changing the extended buffer-to-buffer
credits on the interface. The user cannot configure
the object fcIfAdminRxBbCreditExtended on this
interface.