mw_debug: Add Lattice ECP5 support

mw_debug: Add Lattice ECP5 support

"-b ecp5" will select ECP5 interface that talks to a JTAGG
primitive.

For example with a FT232H JTAG board:

./mw_debug  -t 'ft2232 vid=0x0403 pid=0x6014'  -s 30000000 -b ecp5 mr ff003888 6
Connected to libftdi driver.
Found device ID: 0x41113043
00000000ff003888: 6d6f636c65570a0a  ..Welcom
00000000ff003890: 63694d206f742065  e to Mic
00000000ff003898: 2120747461776f72  rowatt !
00000000ff0038a0: 0000000000000a0a  ........
00000000ff0038a8: 67697320636f5320   Soc sig
00000000ff0038b0: 203a65727574616e  nature:
Core: running
 NIA: c0000000000187f8
 MSR: 9000000000001033

Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>