linux-azure: vmbus-rdma: Use underscore to separate major and minor host OS version

SRU Justification:

Impact:
Currently RDMA drivers names have a dot to separate the major and minor host OS version number (eg, hv_network_directly_142.0.ko). That causes some unexpected behavior with the kmod tools.

modprobe ignores everything after the dot, so it's only possible to load the modules manually with `modprobe hv_network_direct_142` instead of `modprobe hv_network_direct_142.0`.

Also, after the modules is loaded, lsmod shows some errors when searching for `/sys/module/hv_network_direct_142.0` while only `/sys/module/hv_network_direct_142` is available.

Fix: replace dots with underscores to separate major and minor host OS version numbers.

Testcase:
The user should be able to load the drivers with their complete name, eg `modprobe hv_network_direct_142_0` and lsmod should not show any errors after the module is loaded.