Revert "[MLIR][LLVM] Permit integer types in switch other than i32"

This reverts commit 94992670.
Build is broken with:

tools/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.cpp.inc:23996:3: error: no matching function for call to 'printSwitchOpCases'
  printSwitchOpCases(_odsPrinter, *this, getValue().getType(), getCaseValuesAttr(), getCaseDestinations(), getCaseOperands(), getCaseOperands().getTypes());
  ^~~~~~~~~~~~~~~~~~