Bluetooth: Controller: Fix periodic adv data truncation

Advertising data has to be truncated at a PDU boundary

Similar to earlier fix for extended advertising reports

Found in several EBQ tests, including LL/DDI/SCN/BV-25-C,
LL/DDI/SCN/BV-21-C and LL/DDI/SCN/BV-46-C

Signed-off-by: Troels Nilsson <trnn@demant.com>