net: vertexcom: default to disabled on kbuild

Sorry for being rude but new vendors/drivers are supposed to be disabled
by default, otherwise we will have to manually keep track of all vendors
we are not interested in building.

Fixes: 2f207cbf

 ("net: vertexcom: Add MSE102x SPI support")
CC: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>