util: fix golint warnings in csiconfig, volid

golint warns about the following statements:

ceph-csi/internal/util/csiconfig.go
Line 49: warning: exported function Mons should have comment or be unexported (golint)

ceph-csi/pkg/util/volid.go :
Line 72: warning: exported method CSIIdentifier.ComposeCSIID should have comment
or be unexported (golint)

Reported-by: https://goreportcard.com/report/github.com/ceph/ceph-csi
Updates: #975

Signed-off-by: Yug Gupta <ygupta@redhat.com>

internal/util/volid.go

@@ -52,6 +52,11 @@ type CSIIdentifier struct {
 // This maximum comes from the CSI spec on max bytes allowed in the various CSI ID fields
 const maxVolIDLen = 128
 
+const (
+	knownFieldSize = 64
+	uuidSize       = 36
+)
+
 /*
 ComposeCSIID composes a CSI ID from passed in parameters.
 Version 1 of the encoding scheme is as follows,
@@ -64,11 +69,6 @@ Version 1 of the encoding scheme is as follows,
 	Total of constant field lengths, including '-' field separators would hence be,
 	4+1+4+1+1+16+1+36 = 64
 */
-const (
-	knownFieldSize = 64
-	uuidSize       = 36
-)
-
 func (ci CSIIdentifier) ComposeCSIID() (string, error) {
 	buf16 := make([]byte, 2)
 	buf64 := make([]byte, 8)