cmsis_nvic changes required with respect to PR #2518

[fvincenzo]

Once the PR #2518 it is accepted it requires a change in all the CM3 platforms.

Porting uvisor on Beetle required some adaptation of the CMSIS file for the Cortex M3 covered in the patch "Backport virtual NVIC mechanism from CMSIS 5 on CM3". This change impacts even the other platforms that implement cmsis_nvic.c/h.

Please refer to the patch b4d1cfe for the changes required in the other platforms.

[sg-]

We need to create a feature_ branch for updating cmsis core to version 5. Given this is due in September we should aim to release this in mbed OS 5.3

https://github.com/ARM-software/CMSIS_5#cmsis-version-5

[ciarmcom]

ARM Internal Ref: IOTMORF-485