Force sane SRST and TRST initialization

At least some FT2232 based adapters don't necessarily come up
in the expected state, with SRST and TRST disabled.  Since
other adapters could suffer the same problem, let's avoid
needing to patch every driver and just force *all* adapters
to initialize those values properly at server startup.


git-svn-id: svn://svn.berlios.de/openocd/trunk@2824 b42882b7-edfa-0310-969c-e2dbd0fdcd60