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/satamv.c b/satamv.c
index a957505..7fec115 100644
--- a/satamv.c
+++ b/satamv.c
@@ -148,7 +148,7 @@
 
 	/* 512 kByte with two 8-bit latches, and
 	 * 4 MByte with additional 3-bit latch. */
-	return register_par_master(&par_master_satamv, BUS_PARALLEL, 4*MiB, NULL);
+	return register_par_master(&par_master_satamv, BUS_PARALLEL, 0, 4*MiB, NULL);
 }
 
 /* BAR2 (MEM) can map NVRAM and flash. We set it to flash in the init function.