usb: typec: tcpm: Remove unused functions

tcpm_update_source_capabilities() and tcpm_update_sink_capabilities()
are not used anywhere, and I don't recall why I introduced those functions
in the first place. Effectively that means that we don't know if they even
work, or ever did. Lets remove them.

Reported-by: Kyle Tso <kyletso@google.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Kyle Tso <kyletso@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>