package/openvmtools: use correct variable in udev rule RUN+=

package/openvmtools: use correct variable in udev rule RUN+=

DEVPATH is not a valid substitution in a RUN+=, devpath is:
https://mirrors.edge.kernel.org/pub/linux/utils/kernel/hotplug/udev/udev.html

So use that to get rid of the following warning:

Invalid value "/bin/sh -c 'echo 180 >/sys$DEVPATH/device/timeout'" for RUN
(char 27: invalid substitution type), ignoring, but please fix

Source: https://github.com/vmware/open-vm-tools/pull/376

Signed-off-by: Pascal de Bruijn <p.debruijn@unilogic.nl>
Acked-by: Jérémy Rosen <jeremy.rosen@smile.fr>
[Peter: extend description]
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>