wireless/ieee802154: Reworks data_ind allocation to include IOB allocation/deallocation. Hides private data.

wireless/ieee802154: Removes msdu_length from meta-data since it is intrinsically in the IOB

Approved-by: Gregory Nutt <gnutt@nuttx.org>

wireless/ieee802154: Fixes ieee802154_data_ind_s

Approved-by: Gregory Nutt <gnutt@nuttx.org>

STM32L4: add support for many new MCUs from STM32L4X3XX product line and Nucleo-L452 board

Approved-by: Gregory Nutt <gnutt@nuttx.org>

Removes radio IOCTL.  Starts bringing radio and MAC closer with well-defined interface.

Approved-by: Gregory Nutt <gnutt@nuttx.org>

wireless/ieee802154: Removes radio IOCTL.  Starts bringing radio and MAC closer with well-defined interface.

configs/nucleo-l496zg: Kconfig was copied from nucleo-144

Approved-by: Gregory Nutt <gnutt@nuttx.org>

Removed as most options have not been tested.

(This also removes DPFPU/DTCM/ITCM features again, fixing a
recent git history hickup.)

Not tested for any product family, but now it at least compiles.
L496 devices can have one bit wider Volatile Data Segment.

6loWPAN: Local MAC address is fixed by the configuration.  The remote address be with short or extended.

wireless/ieee802154:  Simplifies some primitive prototypes

Approved-by: Gregory Nutt <gnutt@nuttx.org>

STM32L4: stm32l4_i2c: change wrong macro to CONFIG_I2C_POLLED

Approved-by: Gregory Nutt <gnutt@nuttx.org>