qemu: fix memory leak in blockinfo

Coverity flagged commit 0282ca45 as introducing a memory leak;
in all my refactoring to make capacity probing conditional on
whether the image is non-raw, I missed deleting the unconditional
probe.

* src/qemu/qemu_driver.c (qemuStorageLimitsRefresh): Drop
redundant assignment.
Signed-off-by: NEric Blake <eblake@redhat.com>

src/qemu/qemu_driver.c

@@ -11116,9 +11116,6 @@ qemuStorageLimitsRefresh(virQEMUDriverPtr driver,
                                                        buf, len)) < 0)
             goto cleanup;
     }
-    if (!(meta = virStorageFileGetMetadataFromBuf(src->path, buf, len,
-                                                  format, NULL)))
-        goto cleanup;
     if (format == VIR_STORAGE_FILE_RAW)
         src->capacity = src->physical;
     else if ((meta = virStorageFileGetMetadataFromBuf(src->path, buf,