[TableGen] Remove an assumption about the order of encodings in the MVT::SimpleValueType enum. Instead of assuming the types are sorted by size, scan the typeset arrays to find the smallest/largest type. NFC
[TableGen] Remove an assumption about the order of encodings in the MVT::SimpleValueType enum. Instead of assuming the types are sorted by size, scan the typeset arrays to find the smallest/largest type. NFC

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@254589 91177308-0d34-0410-b5e6-96231b3b80d8

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