elf_ops: correct loading of 32 bit PVH kernel

Because sizeof(struct elf64_note) == sizeof(struct elf32_note),
attempting to use the size of the currently defined struct elf_note as
a discriminator for whether the object being loaded is 64 bit in
load_elf() fails.

Instead, take advantage of the existing glue parameter SZ, which is
defined as 32 or 64 in the respective variants of load_elf().

Fixes: 696aa04 ("elf-ops.h: Add get_elf_note_type()")
Signed-off-by: David Edmondson <david.edmondson@oracle.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20210302090315.3031492-2-david.edmondson@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

include/hw/elf_ops.h

@@ -598,9 +598,7 @@ static int glue(load_elf, SZ)(const char *name, int fd,
             nhdr = glue(get_elf_note_type, SZ)(nhdr, file_size, ph->p_align,
                                                *(uint64_t *)translate_opaque);
             if (nhdr != NULL) {
-                bool is64 =
-                    sizeof(struct elf_note) == sizeof(struct elf64_note);
-                elf_note_fn((void *)nhdr, (void *)&ph->p_align, is64);
+                elf_note_fn((void *)nhdr, (void *)&ph->p_align, SZ == 64);
             }
             data = NULL;
         }