multi: fixing it's/its typos in comments

htlcswitch/circuit.go

@@ -56,7 +56,7 @@ func (k *circuitKey) String() string {
 
 // CircuitMap is a data structure that implements thread safe storage of
 // circuit routing information. The switch consults a circuit map to determine
-// where to forward HTLC update messages. Each circuit is stored with it's
+// where to forward HTLC update messages. Each circuit is stored with its
 // outgoing HTLC as the primary key because, each offered HTLC has at most one
 // received HTLC, but there may be multiple offered or received HTLCs with the
 // same payment hash. Circuits are also indexed to provide fast lookups by

htlcswitch/interfaces.go

@@ -10,7 +10,7 @@ import (
 // InvoiceDatabase is an interface which represents the persistent subsystem
 // which may search, lookup and settle invoices.
 type InvoiceDatabase interface {
-	// LookupInvoice attempts to look up an invoice according to it's 32
+	// LookupInvoice attempts to look up an invoice according to its 32
 	// byte payment hash.
 	LookupInvoice(chainhash.Hash) (channeldb.Invoice, error)