x86 asm: Replace .align with .balign

The .align directive used to align storage locations is
ambiguous. On some platforms and assemblers it takes a byte count,
on others the argument is interpreted as a shift value. The current
usage expects the first interpretation.

Replace it with the unambiguous .balign directive which always
expects a byte count, regardless of platform and assembler.

Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Signed-off-by: Attila Fülöp <attila@fueloep.org>
Closes #14422