RootCanal: Fix HCI parsing bottleneck

Current implementation limited the number of HCI packets
parsed to one every 3 ticks. This change modifies the HCI
transport to continue reading from the data channel as long
as information is available.

Test: m root-canal
Bug: 271869468
Change-Id: Ibbfbd7a3fb3c4ca4d085bce9e03b4c8f2df3968d