s390: Handle KCOV __init vs inline mismatches

s390: Handle KCOV __init vs inline mismatches

When KCOV is enabled all functions get instrumented, unless
the __no_sanitize_coverage attribute is used. To prepare for
__no_sanitize_coverage being applied to __init functions, we have to
handle differences in how GCC's inline optimizations get resolved. For
s390 this exposed a place where the __init annotation was missing but
ended up being "accidentally correct". Fix this cases and force a couple
functions to be inline with __always_inline.

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20250717232519.2984886-7-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>