swiotlb: fix a braino in the alignment check fix

The alignment mask in swiotlb_do_find_slots() masks off the high
bits which are not relevant for the alignment, so multiple
requirements are combined with a bitwise OR rather than AND.
In plain English, the stricter the alignment, the more bits must
be set in iotlb_align_mask.

Confusion may arise from the fact that the same variable is also
used to mask off the offset within a swiotlb slot, which is
achieved with a bitwise AND.

Fixes: 0eee5ae1

 ("swiotlb: fix slot alignment checks")
Reported-by: Dexuan Cui <decui@microsoft.com>
Link: https://lore.kernel.org/all/CAA42JLa1y9jJ7BgQvXeUYQh-K2mDNHd2BYZ4iZUz33r5zY7oAQ@mail.gmail.com/
Reported-by: Kelsey Steele <kelseysteele@linux.microsoft.com>
Link: https://lore.kernel.org/all/20230405003549.GA21326@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net/
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Tested-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>