hla_transport: split command registration per transport

hla_transport: split command registration per transport

All the HLA transports (hla_swd and hla_jtag) register the same
set of commands. Such commands are mainly aimed at handling JTAG
compatibility that is required for the transport hla_jtag only.

Split per transport the command registration and limit the
commands to only those required by the transport itself.
Replace the command "hla newtap" with the transport specific
"swd newdap" or "jtag newtap".
Deprecate the command "hla".

Change-Id: I79c78fa97b707482608516d3824151a4d07644c0
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/4877
Tested-by: jenkins