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

Change-Id: I0205d381de331a827435d667c16297aaf5bb609e
Signed-off-by: Shawn Shan <shawn.shan@arm.com>

These file changes provide small fixes for various targets
on MPS2 platform in order to work properly and pass all
Greentea test cases. The __initial_sp has been explicitly set
in the targets' startup files, and also INITIAL_SP has been
given a different value. The values have been extracted from
the specific targets' Application Note documentation.
Affected targets are: ARM_MPS2_M0, ARM_MPS2_M0P, ARM_MPS2_M3,
ARM_MPS2_M4 and ARM_MPS2_M7.

Change-Id: I3d5d0e1ae386cdcc3ba5eb63be929267a257b139
Signed-off-by: Bence Kaposzta <bence.kaposzta@arm.com>

targets/cmsis -> cmsis
targets/cmsis/TARGET_* -> targets/TARGET_*/device
targets/cmsis/TARGET_*/mbed_rtx.h -> targets/TARGET_*/mbed_rtx.h