Fix KATADC 3-wire chip select for ZDOK1 on ROACH2

The KATADC 3-wire chip select signal for ZDOK1 on ROACH2 had the wrong
polarity.  This commit fixes that problem.
Fix KATADC 3-wire clock for ROACH2 ZDOK1

The KATADC 3-wire clock for ROACH2 ZDOK1 was being driven by the 3-wire clock
for ZDOK0.  This made it impossible to program a KATADC chip in ZDOK1 on
ROACH2.  This commit fixes that particular problem.
Fix OPB clock for three ADC blocks on ROACH2

For some reason, three ADC blocks on ROACH2 had their OPB clock driven by
sys_clk instead of epb_clk.  This restores those blocks to use epb_clk for
their OPB clock source (like every other OPB block in the system).