Add SPDX license identifier to Arm files ...

Add license identifier to files which Arm owns the copyright to,
and contain either BSD-3 or Apache-2.0 licenses. This is to address
license errors raised by scancode analysis.

Added support for ADI EV-COG-AD3029LZ platform. ...

Fixed issues raised from ARM PR review and removed the unsupported platform.

- Fixed an issue where the TRNG is read even though it may not be ready;
- Added configuration to ensure the buffering mode is disabled so only 8-bit bytes are generated;
- Moved the TRNG device handle into the trng_t structure.

Removed undefined spi slave related functions.

- Added error checking for trng_get_bytes function;
- Added curly brackets to single line conditions for some files;
- Changed rx and tx buffers in serial module as local variables;
- Removed some unused code and some minor formatting corrections;
- Minor i2c & spi updates for github pull request;
- Added function definition for spi_master_block_write.

Added default delay and sample times for the ADC during initialization.

- Added code to clear stack variable in trng_get_bytes upon exiting the
function;
- Remove lp ticker functionality as the timer hardware does not satisfy
lp timer requirements.

Added a check for the STUCK bit before reading the RNG data register to ensure there are no hardware faults.

- Removed .mbedignore to work around some exporter issues;
- Added #includes to some of the driver data C files for them to build on their own.

Removed the custom app thread stack size.

Fixed issues raised in the feedback from ARM for the ADuCM4050 platform.

Added support for ADI EV-COG-AD4050LZ platform.