[v4] iommu/riscv: prevent NULL deref in iova_to_phys

[XianLiang Huang]

> I suggest to take another look for the better distinction of mentioned key words.
I misunderstood this
    >> …> Check the pointer before using it to avoid the bug. …
    > Would a summary phrase like “Prevent null pointer dereference in riscv_iommu_iova_to_phys()”
    > be also helpful?
https://lore.kernel.org/lkml/effb29be-6d14-47e5-ab71-454119467750@web.de/

>> > Changes
>> > v4:
>> > - Change the summary as Markus recommends
>> > 
>> > v3:
>> > - Remove redundant pte validation in riscv_iommu_iova_to_phys
>> > - Improve subject line to emphasize prevention
> Does anything hinder you to integrate repeated patch review ideas better
> into your contributions?
Do you suggest merge the repeated patch changlogs?
may a RESEND v3:
- Remove redundant pte validation in riscv_iommu_iova_to_phys
- Improve summary and description to emphasize prevention as Markus recommends

Regards,
Xianliang