Patch submitted from Trac #64
Seems certain clones do not correctly emulate the ftdi chip, if
the call to read the latency timer fails then do not treat this as a
failure.
Change-Id: Iae671b926d101adf1010639d11ca46c58d0af524
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/1627
Tested-by: jenkins
Reviewed-by: Xiaofan <xiaofanc@gmail.com>