main: friendlier error message on wrong number of arguments

Before:
	Usage: gocryptfs [OPTIONS] CIPHERDIR MOUNTPOINT

After:
	Wrong number of arguments (have 9, want 2). You passed: "-nosyslog" "." "asd" "-q" "ß" "asdf" "fg" "gh" "sdf" "asd fs\\dfg"
	Usage: gocryptfs [OPTIONS] CIPHERDIR MOUNTPOINT

1 files changed, 0 insertions, 4 deletions

diff --git a/mount.go b/mount.go
index 3157332..803b09b 100644
--- a/mount.go
+++ b/mount.go
@@ -26,10 +26,6 @@ import (
 // Called from main.
 func doMount(args *argContainer) int {
 	// Check mountpoint
-	if flagSet.NArg() != 2 {
-		tlog.Fatal.Printf("Usage: %s [OPTIONS] CIPHERDIR MOUNTPOINT", tlog.ProgramName)
-		os.Exit(ErrExitUsage)
-	}
 	var err error
 	args.mountpoint, err = filepath.Abs(flagSet.Arg(1))
 	if err != nil {