Bluetooth: Controller: Fix BT_CTLR_ADV_DATA_LEN_MAX Kconfig dependency

Fix BT_CTLR_ADV_DATA_LEN_MAX and other Kconfig dependencies,
and clean up the use of PDU_AC_LL_SIZE_MAX which is used to
allocate scratch packet to be atleast able to accommodate
the minimum 31 bytes AD data such that it is sufficient to
transmit and/or receive scan response PDUs when either
broadcaster or observer alone is supported.

Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>