(Reuters) - Chipmaker NXP Semiconductors said on Wednesday it had idled two manufacturing plants in Austin, Texas as a historic winter storm gripped much of the state, forcing utility companies to curb their services. “Austin-area utility providers are prioritizing service to residential areas,” the company said in a statement, adding that it was notifying affected customers of potential supply disruptions. The winter storm in Texas has killed at least 21 people, left millions of Texans without power and spun killer tornadoes into the U.S. Southeast on Tuesday.