coresight: add sw usb mode support for tmc

Add SW USB mode support for TMC to use software interface
to send data from TMC to USB.

Change-Id: I8e4dee6cfd037d8bb81ea27ad2ed996e9980720c
Signed-off-by: Shaoqing Liu <shaoqingliu@codeaurora.org>
Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>