According to the following reference, a few tons of infalling space dust cause the Martian clouds: https://www.sciencedaily.com/releases/2019/06/190617125120.htm. These clouds can boost local surface temperatures by up to 20 Kelvin. Could we boost this effect by mass driving crushed dust from Phobos into the Mars atmosphere? 10 tons a day would already be a factor of 4 increase.
Meteorology is a nasty science: there are a lot of interactions, feed-back and feed-forward, making hard to evaluate the effect of a single element.
What you read in that article comes from the dust acting as condensation nuclei and leading to cloud formation.
However, more dust in the high atmosphere means also more solar light reflected back into space (Krakatoa and Pinatubo eruptions, nuclear winter, all those are due to this). This makes me think that the increase of temperature due to the higher cloud coverage could be easily canceled by the lowered solar irradiation resulting from the dust in high atmosphere.
Even if this was not the case, by just increasing the temperature you won't terraform Mars. You also need to have more water and more gases in the atmosphere, and a magnetic field to shield solar wind. By just increasing the temperature you just increase the net loss of gases from Mars, due to the increased fraction of them reaching escape velocity.