memory_bus: Turn flashbase into a par_master member `rom_base`

Get rid of the global `flashbase`. Treat overrides for the `rom_base`
similar to `max_rom_decode`: Gather the information in `internal_data`
and then pass it to register_par_master().

Change-Id: Ib9ed7234a849fe3550200fd602226d0036da15f0
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.sourcearcade.org/c/flashprog/+/436
diff --git a/parallel.c b/parallel.c
index 3e32d59..d8a751e 100644
--- a/parallel.c
+++ b/parallel.c
@@ -64,7 +64,7 @@
 }
 
 int register_par_master(const struct par_master *mst, const enum chipbustype buses,
-			const size_t max_rom_decode, void *data)
+			const uintptr_t rom_base, const size_t max_rom_decode, void *data)
 {
 	struct registered_master rmst = { 0 };
 
@@ -86,6 +86,8 @@
 
 	rmst.buses_supported = buses;
 	rmst.par = *mst;
+
+	rmst.par.rom_base = rom_base;
 	if (data)
 		rmst.par.data = data;