These changes are for TFM_DUALCPU and TFM_V8M platforms.
The initialization happens after mbed-os kernel is kicked off and
when the thread is up and running.
We are initializing the following for TFM_DUALCPU platforms:
* IPC Interrupts for syncing multi-core platforms.
* NS Mailbox to receive messages.
* NS interface.
We are only initializing Non-secure interface for TFM_V8M platforms.
mbed_tfm_init() in tfm_mbed_boot.c overrides the WEAK mbed_tfm_init()
for a specific platform.
Signed-off-by: Vikas Katariya <vikas.katariya@arm.com>