trivial: style allocman utspace code

Fix all the whitespace

- remove trailing whitespace
- remove duplicate blank lines
- remove blank lines at end of files

Fix licenses

libsel4allocman: Memory mapped device IO allocation support

Adds support at the top level allocman interface for allocating
objects at a particular physical address (allocman_utspace_alloc_at)
as well as fullfilling allocations from 'device memory'. Uses this
for implementing the additional vka interface function vka_utspace_alloc_at

The split and twinkle untyped allocators are updated to support this
new interface. split implements the 'alloc_at' by brute force searches
over its untypeds, whilst twinkle with its lack of book keeping
is forced to fail any 'alloc_at' request

Fix: comply with _utspace_twinkle_free declaration at twinkle.h

Remove all references to KERNEL_STABLE

libsel4allocman: Make allocman 64-bit friendly

When compiling for 32-bit there may be spurious warnings due to
some interface type changes. These will eventually be fixed when
other libraries are made 64-bit compatible