drivers: hwinfo: add driver for TI SimpleLink CC13xx/CC26xx series

Introduce hwinfo driver for Texas Instruments SimpleLink CC13xx/CC26xx
SOC series, with support for retrieving device's ID and cause of reset.

By default, the pre-programmed, 8-bytes length IEEE MAC address is used
for device's ID, with option ('HWINFO_CC13XX_CC26XX_USE_BLE_MAC') for
use 6-bytes length BLE MAC instead. By default, read-only values stored
in FCFG (Factory Configuration) are used but additional Kconfig option
('HWINFO_CC13XX_CC26XX_ALWAYS_USE_FACTORY_DEFAULT') is also provided,
which allows to use values from writable CCFG (Customer Configuration)
area. In all cases, device ID value is provided in big-endian which
matches what TI's UniFlash tool returns.

For reset cause, 'SysCtrlResetSourceGet()' function from TI's driver
library is used and its value is mapped to Zephyr's implementation.
Importantly, only root cause of reset is available on CC13xx/CC26xx
platform as described in MCU Technical Reference Manual ('RESET_SRC'
field in 'RESETCTL' register):

  "Shows the root cause of the last system reset. More than the
   reported reset source can have been active during the last
   system reset but only the root cause is reported."

Signed-off-by: Piotr Dymacz <pepe2k@gmail.com>