Convert to SPDX license tags

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

Style: Updated style of modified files

Updated the style of various source files recently updated.

libsel4vm: Updated WIDTH_DOUBLEWORD fault mask

Updated the WIDTH_DOUBLEWORD fault mask to account for 64bit
values.

Co-authored-by: Anna Lyons <anna@gh.st>

libsel4vm: Trival fixups to arm 'fault_init'

These are small fixups to the arm 'fault_init' function, using
the correct type for the error code and calloc'ing the
fault datastructure to ensure zero'd state.

libsel4vm: Added 'fault_set_ctx' helper

Added a helper to set the fault user context registers. This
overrides the context registers if the user wishes to manipulate
the entire context state.

libsel4vm: Revised arm fault types

Added a new field in the arm fault data-structure that
consolidates the different types the fault can represent. This
being a DATA,PREFETCH or VCPU fault. It previously only assumed
the fault could be a data or prefetch fault when advancing or
manipulating the faults state. Updated various function names to
reflect the new types.

libsel4vm: Changed wfi fault to general vcpu fault

Generalised the function 'new_wfi_fault' such that it can be used
for other vcpu faults. This additionally removes the 'is_wfi'
field since we record the hsr value in the fault object.

libsel4vm: Made arm fault interface private

The arm fault interface is only used internally as external
source uses the vcpu fault interface instead. Moved and
consolidated the fault interface into the internal arm sources.