memory: Simplify memory_region_init_ram_from_fd() calls

Mechanical change using the following coccinelle script:

@@
expression mr, owner, arg3, arg4, arg5, arg6, arg7, errp;
@@
-   memory_region_init_ram_from_fd(mr, owner, arg3, arg4, arg5, arg6, arg7, &errp);
    if (
-       errp
+       !memory_region_init_ram_from_fd(mr, owner, arg3, arg4, arg5, arg6, arg7, &errp)
    ) {
        ...
        return;
    }

and removing the local Error variable.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Message-Id: <20231120213301.24349-6-philmd@linaro.org>

system/memory.c

@@ -3577,11 +3577,8 @@ void memory_region_init_ram(MemoryRegion *mr,
                             Error **errp)
 {
     DeviceState *owner_dev;
-    Error *err = NULL;
 
-    memory_region_init_ram_nomigrate(mr, owner, name, size, &err);
-    if (err) {
-        error_propagate(errp, err);
+    if (!memory_region_init_ram_nomigrate(mr, owner, name, size, errp)) {
         return;
     }
     /* This will assert if owner is neither NULL nor a DeviceState.