arm: move arch specific grant table bits into grant_table.c

arm: move arch specific grant table bits into grant_table.c

Instead of attaching the ARM specific grant table data to the domain
structure add it to struct grant_table. Add the needed arch functions
to the asm-*/grant_table.h includes.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Julien Grall <julien.grall@arm.com>