bpf: fix a typo

Change-Id: I5b865483bf6a8bba07934ae3b1ff5bbbf6dd6a00
Reviewed-on: https://go-review.googlesource.com/24240
Reviewed-by: Matt Layher <mdlayher@gmail.com>
Reviewed-by: Tom Heng <zhm20070928@gmail.com>
Reviewed-by: Michael Hudson-Doyle <michael.hudson@canonical.com>

bpf/vm_test.go

@@ -112,7 +112,7 @@ func ExampleNewVM() {
 		0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
 		0x00, 0x11, 0x22, 0x33, 0x44, 0x55,
 		0x08, 0x06,
-		// Payload ommitted for brevity
+		// Payload omitted for brevity
 	}
 
 	// Run our VM's BPF program using the Ethernet frame as input