Debian (and probably lots of other distributions), do not enable unsafe VFIO
option (CONFIG_VFIO_NOIOMMU). If that is true, then the module parameter does
not exist.

This causes DPDK devbind to fail:
Error: failed to check unsafe noiommu mode - Cannot open
/sys/module/vfio/parameters/enable_unsafe_noiommu_mode: [Errno 2] No such file
or directory: '/sys/module/vfio/parameters/enable_unsafe_noiommu_mode'


This regression is caused by the commit.

commit 6ca0f1c8450d6e28926cad33c6500ad487f4cfdb
Author: Fidaullah Noonari <fidaullah.noonari@emumba.com>
Date:   Wed Oct 2 11:13:12 2024 -0700

    usertools/devbind: support VFIO non-IOMMU mode

    This patch adds noiommu option to dpdk-devbind.
    If the no IOMMU is detected, then if noiommu flag is set
    the vfio-pci unsafe_noiommu_mode flag is set.

    Signed-off-by: Fidaullah Noonari <fidaullah.noonari@emumba.com>
    Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
    Acked-by: Bruce Richardson <bruce.richardson@intel.com>