usb: pd: Don't retry sending Source Capabilities if PD capable

If connected to a sink that we already know is PD capable, the
next time Source Capabilities is sent, whether due to reset or
in response Get_Source_Capabilities, upon failure should not
retry for nCapsCount times. Instead, simply issue a Soft Reset.

Change-Id: I5a53073f5473575e7206e1fdd344b8f14affddc2
Signed-off-by: Jack Pham <jackp@codeaurora.org>