Hcidoc: Use hci_packets.pdl in rootcanal

The hci_packets.pdl in system/pdl doesn't seem to be fully compatible
with the pdl-compiler. Therefore, use the one in rootcanal instead.

Since they have different structure, some adjustments needs to be made.
In particular, this one doesn't have nested HCI structure, and doesn't
have GAP Data implementation.

Bug: 289858128
Test: m -j
Test: Manual verification
Flag: EXEMPT, floss only changes
Change-Id: I0ede46f80cc0e371bc69ccdbd9f2b60e9be6ccd8