ossl: Add missing labels to bsaes-armv7.S

There is a bug in the OpenSSL script which generates this file; the bug
is in the process of being fixed upstream.

Specifically, when generating the output, bsaes-armv7.pl strips some
labels that are used when the output asm is compiled with KERNEL
defined, resulting in a build error. As a step towards adding armv7
support to ossl(4), manually patch the generated asm. The upstream fix
will be imported later.

Reviewed by: andrew, jhb, emaste
MFC after: 1 week
Sponsored by: Klara, Inc.
Sponsored by: Stormshield
Differential Revision: https://reviews.freebsd.org/D41303