powerpc/nvram: Add missing kfree in error path

If 'nvram_write_header' fails, then 'new_part' should be freed, otherwise,
there is a memory leak.

Signed-off-by: Christophe Jaillet <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>

arch/powerpc/kernel/nvram_64.c

···
 	if (rc <= 0) {
 		pr_err("nvram_create_os_partition: nvram_write_header "
 		       "failed (%d)\n", rc);
+		kfree(new_part);
 		return rc;
 	}
 	list_add_tail(&new_part->partition, &free_part->partition);