tools: arm: prepare domain builder for multiple banks of guest RAM

tools: arm: prepare domain builder for multiple banks of guest RAM

Prepare for adding more banks of guest RAM by renaming a bunch of defines
as RAM0 and replacing variables with arrays and introducing loops.

Also in preparation switch to using GUEST_RAM0_BASE explicitly instead of
implicitly via dom->rambase_pfn (while asserting that they must be the same).
This makes the multiple bank case cleaner (although it looks a bit odd for
now).

GUEST_RAM_BASE is defined as the address of the lowest RAM bank, it is used in
tools/libxl/libxl_dom.c to call xc_dom_rambase_init().

Lastly for now ramsize (total size) and rambank_size[0] (size of first bank)
are the same, but use the appropriate one for each context.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>