IB/hfi1: Correct guard on eager buffer deallocation

The code tests the dma address which legitimately can be 0.

The code should test the kernel logical address to avoid leaking eager
buffer allocations that happen to map to a dma address of 0.

Fixes: 60368186 ("IB/hfi1: Fix user-space buffers mapping with IOMMU enabled")
Link: https://lore.kernel.org/r/20211129191952.101968.17137.stgit@awfm-01.cornelisnetworks.com


Signed-off-by: Mike Marciniszyn <mike.marciniszyn@cornelisnetworks.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>