memory_bus: Move related declarations into new `chipdrivers/memory_bus.h`

Change-Id: I2bef65de77860d049ec3d9938ae777c5f929c258
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.sourcearcade.org/c/flashprog/+/438
diff --git a/sst28sf040.c b/sst28sf040.c
index fb3fea6..6c22591 100644
--- a/sst28sf040.c
+++ b/sst28sf040.c
@@ -17,7 +17,7 @@
  */
 
 #include "flash.h"
-#include "chipdrivers.h"
+#include "chipdrivers/memory_bus.h"
 
 #define AUTO_PG_ERASE1		0x20
 #define AUTO_PG_ERASE2		0xD0