iommu/amd: Add missing spin_lock initialization

commit 2c13d47a1a7ee8808796016c617aef25fd1d1925 upstream.

Add missing spin_lock initialization in
amd_iommu_bind_pasid() function and make lockdep happy
again.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>