sperating tx2_smmu from arm_smmu

Signed-off-by: Oliver Scott <Oliver.Scott@data61.csiro.au>

trivial: style changed files

vspace: extend map object to io and ept structures

This will allow the same code to be used irrespective of the type of
paging structions used

vspace: add page map fn type and iospace wrapper

This allows all page mapping functions we currently use to have the
same type signature.

vspace: add mapping abstraction

This commit provides a mapping object which can be obtained for any
architecture and used to map paging structures based on the number of
bits left to resolve in an address.