In kmem_cache_create(): always check if BYTES_PER_WORD is less than
ARCH_SLAB_MINALIGN and disable debug options that would set the
alignment to BYTES_PER_WORD.
This will make sure that all slab caches will have at least an
ARCH_SLAB_MINALIGN alignment.
In addition make sure that a caller mandated align which is greater
than BYTES_PER_WORD also disables the same debug options.
This makes sure that ARCH_KMALLOC_MINALIGN also has an effect if
CONFIG_DEBUG_SLAB is set.