libct/cg/fscommon: use strings.Cut in RDMA parser

Using strings.Cut (added in Go 1.18, see [1]) results in faster and
cleaner code with less allocations (as we're not using a slice).

Also, use switch in parseRdmaKV.

[1]: golang/go#46336

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

libcontainer/cgroups/fscommon/rdma.go

@@ -17,14 +17,12 @@ import (
 func parseRdmaKV(raw string, entry *cgroups.RdmaEntry) error {
 	var value uint32
 
-	parts := strings.SplitN(raw, "=", 3)
+	k, v, ok := strings.Cut(raw, "=")
 
-	if len(parts) != 2 {
+	if !ok {
 		return errors.New("Unable to parse RDMA entry")
 	}
 
-	k, v := parts[0], parts[1]
-
 	if v == "max" {
 		value = math.MaxUint32
 	} else {
@@ -34,9 +32,10 @@ func parseRdmaKV(raw string, entry *cgroups.RdmaEntry) error {
 		}
 		value = uint32(val64)
 	}
-	if k == "hca_handle" {
+	switch k {
+	case "hca_handle":
 		entry.HcaHandles = value
-	} else if k == "hca_object" {
+	case "hca_object":
 		entry.HcaObjects = value
 	}