PCI/IOV: Remove group write permission from sriov_numvfs, sriov_drivers_autoprobe

Previously the sriov_numvfs and sriov_drivers_autoprobe sysfs files had
0664 permissions, which allowed group write.  libvirt runs as root when
dealing with PCI, and it chowns files needed by qemu, so group write
permission should not be needed.

Change these permissions from 0664 to 0644, which is what DEVICE_ATTR_RW()
does by default.

[bhelgaas: commit log]
Link: https://lore.kernel.org/r/20190905063226.43269-1-skunberg.kelsey@gmail.com
Link: https://lore.kernel.org/r/850cf536-0b72-d78c-efaf-855dcb391087@redhat.com


Signed-off-by: Kelsey Skunberg <skunberg.kelsey@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Donald Dutile <ddutile@redhat.com>