NEW YORK (Reuters) -Arm, the chip designer owned by SoftBank Group Corp, received enough backing from investors to secure at least the top end of the price range in its initial public offering, which would command a $54.5 billion valuation on a fully diluted basis, a person familiar with the matter said on Tuesday. After reviewing investor commitments on Tuesday, Arm decided it will only accept the top end of its indicated $47-to-$51-per-share range, or a price that is even higher, the source said. Arm may price its IPO above the indicated price range and will decide on how much it will sell...