Change interpreter program from armcc to armclang. Pass it different
optional arguments: specify the target compiler and core core type.

Workaround a bug where the boot stack size configuration option is not
passed on to armlink, the Arm Compiler's linker. Prefer
MBED_CONF_TARGET_BOOT_STACK_SIZE if present, as this is what the
configuration system should provide. Fall back to MBED_BOOT_STACK_SIZE
if MBED_CONF_TARGET_BOOT_STACK_SIZE is not defined, as in the case of
buggy tools. If both MBED_CONF_TARGET_BOOT_STACK_SIZE and
MBED_BOOT_STACK_SIZE are not defined, then we fall back to a hard-coded
value provided by the linkerscript. See
https://github.com/ARMmbed/mbed-os/issues/13474 for more information.

To allow overriding of the boot stack size from the Mbed configuration
system, consistently use MBED_CONF_TARGET_BOOT_STACK_SIZE rather than
MBED_BOOT_STACK_SIZE.

Fixes #10319

- fix compiler warning message of flash_api.c
- eliminate absolute address of ROM tables
- add MBED_APP_START and MBED_APP_SIZE to linker scripts

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.