xlat lib v2: Expose *_ctx() APIs

xlat lib v2: Expose *_ctx() APIs

In a previous patch, the xlat_ctx_t type has been made public.
This patch now makes the *_ctx() APIs public.

Each API now has a *_ctx() variant. Most of them were already implemented
and this patch just makes them public. However, some of them were missing
so this patch introduces them.

Now that all these APIs are public, there's no good reason for splitting
them accross 2 files (xlat_tables_internal.c and xlat_tables_common.c).
Therefore, this patch moves all code into xlat_tables_internal.c and
removes xlat_tables_common.c. It removes it from the library's makefile
as well.

This last change introduces a compatibility break for platform ports
that specifically include the xlat_tables_common.c file instead of
including the library's Makefile. The UniPhier platform makefile has
been updated to now omit this file from the list of source files.

The prototype of mmap_add_region_ctx() has been slightly changed. The
mmap_region_t passed in argument needs to be constant because it gets
called from map_add(), which receives a constant region. The former
implementation of mmap_add() used to cast the const qualifier away,
which is not a good practice.

Also remove init_xlation_table(), which was a sub-function of
init_xlat_tables(). Now there's just init_xlat_tables() (and
init_xlat_tables_ctx()). Both names were too similar, which was
confusing. Besides, now that all the code is in a single file,
it's no longer needed to have 2 functions for that.

Change-Id: I4ed88c68e44561c3902fbebb89cb197279c5293b
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>