Taiwan Semiconductor shares had a rough day, but it's a stock that "everyone should want to own" at these levels, according to Tim Seymour, founder and chief investment officer of Seymour Asset Management. U.S.-traded shares of the chip giant dropped as much as 4.2% on Monday after the company posted a decline in monthly revenue for the first time in nearly four years . The stock ultimately trimmed losses and ended the day about 1.4% lower. "You want any chance to buy this stock on weakness," Seymour said on CNBC's "Fast Money." "Right now, that's a stock everyone should want…