opts: NormalizeCapability(): fix redefinition of the built-in function (revive)

opts/capabilities.go:25:2: redefines-builtin-id: redefinition of the built-in function cap (revive)
        cap = strings.ToUpper(strings.TrimSpace(cap))
        ^
    opts/capabilities.go:30:3: redefines-builtin-id: redefinition of the built-in function cap (revive)
            cap = "CAP_" + cap
            ^

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

opts/capabilities.go

@@ -21,15 +21,15 @@ const (
 // This function only handles rudimentary formatting; no validation is performed,
 // as the list of available capabilities can be updated over time, thus should be
 // handled by the daemon.
-func NormalizeCapability(cap string) string {
-	cap = strings.ToUpper(strings.TrimSpace(cap))
-	if cap == AllCapabilities || cap == ResetCapabilities {
-		return cap
+func NormalizeCapability(capability string) string {
+	capability = strings.ToUpper(strings.TrimSpace(capability))
+	if capability == AllCapabilities || capability == ResetCapabilities {
+		return capability
 	}
-	if !strings.HasPrefix(cap, "CAP_") {
-		cap = "CAP_" + cap
+	if !strings.HasPrefix(capability, "CAP_") {
+		capability = "CAP_" + capability
 	}
-	return cap
+	return capability
 }
 
 // CapabilitiesMap normalizes the given capabilities and converts them to a map.