habanalabs: restore vm_pgoff after mmap

Due to using dma_mmap_coherent() to perform mmap of dma memory, we
had to clear the vm_pgoff field before calling that function.

However, that broke the userspace (profiler tool) as they relied
on searching the /proc/self/maps for these values to correctly
"disassemble" the topology recipe.

To re-enable that functionality, the driver can simply restore the
value of vm_pgoff before returning to userspace but after calling
dma_mmap_coherent().

Signed-off-by: Oded Gabbay <ogabbay@kernel.org>

drivers/misc/habanalabs/common/command_buffer.c

@@ -517,6 +517,7 @@ int hl_cb_mmap(struct hl_fpriv *hpriv, struct vm_area_struct *vma)
 	}
 
 	cb->mmap_size = cb->size;
+	vma->vm_pgoff = handle;
 
 	return 0;