[PATCH v2] tty: serial: samsung_tty: loopback mode support

[Chanho Park]

> > We can test it by linux-serial-test program with -k option. The tool
> > will set TIOCM_LOOP mode when the option is specified.
> > -k, --loopback     Use internal hardware loop back
> 
> Again, what does this line mean in a changelog text?

I put the option to refer how the tool can use. I can see it is not related
with this commit.
I'll remove them next patch.

> 
> And properly wrap your lines at 72 columns.

I'll keep that in mind.
Thanks for your review :)

Best Regards,
Chanho Park