iommu: msm: Add call to set client name during attach_dev

client_name for a domain was initally set from
msm_register_domain. But now since we have
deprecated msm_register_domain functionality,
client name was never set making it difficult
to identify which domain belongs to which client.
Add explicit call to ensure client name is set
in attach_dev.

Change-Id: Id51b62a6b92a897dea5e8df6af55b107d33572a5
Signed-off-by: Susheel Khiani <skhiani@codeaurora.org>