- Update git references to mcu-driver-hal and
  mcu-driver-reference-platforms-for-arm, and use streamlined CMake
targets from both.
- Remove references to mcu-driver-bootstrap that is no longer provided
  by mcu-driver-hal, and replace with standalone components (i.e.
mbed-critical, for the critical section).
- Remove definitions for generic cmsis-core and cmsis-startup-cortex-m
  CMake targets from the cmsis-5 SDK component. These targets are
insufficient (they do not cover all the functionality) even for our
reference platforms. If the application chooses to use reference
implementation for Arm, the CMSIS-related CMake targets are provided
alongside the HAL implementation. This will be also the case for other
(not reference) platforms.
- As a direct replacement for cmsis-core, define
  iotsdk-cmsis-core-device, an interface target providing
platform-specific CMSIS-Core features that all the components can link
to if required. The SDK user has to explicitly link their platform to
this target.
- Use the updated function signature for mps3_uart_init().

Signed-off-by: Filip Jagodzinski <filip.jagodzinski@arm.com>