As its not used outside iommu.c. Also rename it as dev_flush_pasid_all().

No functional change intended.
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Link: https://lore.kernel.org/r/20240828111029.5429-6-vasant.hegde@amd.comSigned-off-by: Joerg Roedel <jroedel@suse.de>