samples/livepatch: add module descriptions

Every module should have a description, so add one for each of these modules.

[akpm@linux-foundation.org: match the livepatch-callbacks-mod.c description, per Petr]
Link: https://lkml.kernel.org/r/20250324173242.1501003-3-arnd@kernel.org


Fixes: 6c6c1fc0 ("modpost: require a MODULE_DESCRIPTION()")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Easwar Hariharan <eahariha@linux.microsoft.com>
Cc: Jeff Johnson <jeff.johnson@oss.qualcomm.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Stehen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>