memory: Simplify memory_region_init_rom_device_nomigrate() calls

Mechanical change using the following coccinelle script:

@@
expression mr, owner, arg3, arg4, arg5, arg6, errp;
@@
-   memory_region_init_rom_device_nomigrate(mr, owner, arg3, arg4, arg5, arg6, &errp);
    if (
-       errp
+       !memory_region_init_rom_device_nomigrate(mr, owner, arg3, arg4, arg5, arg6, &errp)
    ) {
        ...
        return;
    }

and removing the local Error variable.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Message-Id: <20231120213301.24349-10-philmd@linaro.org>

system/memory.c

@@ -3627,12 +3627,9 @@ void memory_region_init_rom_device(MemoryRegion *mr,
                                    Error **errp)
 {
     DeviceState *owner_dev;
-    Error *err = NULL;
 
-    memory_region_init_rom_device_nomigrate(mr, owner, ops, opaque,
-                                            name, size, &err);
-    if (err) {
-        error_propagate(errp, err);
+    if (!memory_region_init_rom_device_nomigrate(mr, owner, ops, opaque,
+                                                 name, size, errp)) {
         return;
     }
     /* This will assert if owner is neither NULL nor a DeviceState.