[PATCH] Hotplug: Make dev->bus checking consistent

Earlier in the same function dev->bus is checked before dereferenced,
make consistent although I honestly don't know if dev->bus could
ever be NULL

Found by the Coverity tool

Signed-off-by: Alexander Nyberg <alexn@dsv.su.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>