build: enable unconvert linter (#15456)

* build: enable unconvert linter

 - fixes #15453
 - update code base for failing cases

* cmd/puppeth: replace syscall.Stdin with os.Stdin.Fd() for unconvert linter

swarm/storage/chunker.go

@@ -205,9 +205,9 @@ func (self *TreeChunker) split(depth int, treeSize int64, key Key, data io.Reade
 	}
 	// dept > 0
 	// intermediate chunk containing child nodes hashes
-	branchCnt := int64((size + treeSize - 1) / treeSize)
+	branchCnt := (size + treeSize - 1) / treeSize
 
-	var chunk []byte = make([]byte, branchCnt*self.hashSize+8)
+	var chunk = make([]byte, branchCnt*self.hashSize+8)
 	var pos, i int64
 
 	binary.LittleEndian.PutUint64(chunk[0:8], uint64(size))

swarm/storage/memstore.go

@@ -78,7 +78,7 @@ type memTree struct {
 func newMemTree(b uint, parent *memTree, pidx uint) (node *memTree) {
 	node = new(memTree)
 	node.bits = b
-	node.width = 1 << uint(b)
+	node.width = 1 << b
 	node.subtree = make([]*memTree, node.width)
 	node.access = make([]uint64, node.width-1)
 	node.parent = parent

swarm/storage/pyramid.go

@@ -327,7 +327,7 @@ func (self *PyramidChunker) loadTree(chunkLevel [][]*TreeEntry, key Key, chunkC
 	// Add the root chunk entry
 	branchCount := int64(len(chunk.SData)-8) / self.hashSize
 	newEntry := &TreeEntry{
-		level:         int(depth - 1),
+		level:         depth - 1,
 		branchCount:   branchCount,
 		subtreeSize:   uint64(chunk.Size),
 		chunk:         chunk.SData,
@@ -352,7 +352,7 @@ func (self *PyramidChunker) loadTree(chunkLevel [][]*TreeEntry, key Key, chunkC
 				}
 				bewBranchCount := int64(len(newChunk.SData)-8) / self.hashSize
 				newEntry := &TreeEntry{
-					level:         int(lvl - 1),
+					level:         lvl - 1,
 					branchCount:   bewBranchCount,
 					subtreeSize:   uint64(newChunk.Size),
 					chunk:         newChunk.SData,