Convert to SPDX license tags

Signed-off-by: Gerwin Klein <gerwin.klein@data61.csiro.au>

trivial: Style changed files

libsel4vm*: Switch malloc calls to calloc

Reduces chances of an uninitialised structure being used and causing
issues that are painful to debug.

libsel4vm: Moved memory utils into vmmplatsupport

Moved the guest memory utils interface into libsel4vmmplatsupport.
This interface better exists in libsel4vmmplatsupport as its more
relevant to support vmm devices and drivers. This in turn
simplifies libsel4vm's interfaces.

libsel4vm: default error callback out of mem utils

Moved the function 'default_error_fault_callback' out of
the guest memory utils interface and into its own interface
'guest_memory_helpers'. The intention is to eventually move
guest memory utils out of libsel4vm but we want to keep the
'default_error_fault_callback'.

libsel4vmmplatsupport: device_utils use libsel4vm

Updated the device_utils to use libsel4vm for
registering device memory regions and fault handlers.
This is a general update to the device utils source to use
the updated interfaces in libsel4vm and libsel4vmmplatsupport.
Prior to this update device_utils would not compile/work.

sel4vmmplatsupport: Moved unsupported device utils

Moved unsupported device utils into sel4vmmplatsupport. This code
will NOT compile. The code moved needs to be re-evaluated and
updated to use a new memory interface and device registration
interface. This is being moved now as its currently incompatible
with the new memory interface and will need to be re-assessed in
future updates.