[evlatests] bandpass tool update

[Walter Brisken]

Over the last 2 days I did find a couple bugs in the bandpass tool.  Now 
K, Ka, and Q bands should work and provide the correct frequency scale 
when the UX converter straight path is used.

When using the converted path through the UX converter for either IF pair, 
neither IF pair will show the correct frequency labeling -- the program 
may in fact refuse to run.  This is because it is currently impossible to 
read the value of the band select switch when the converted path is used 
-- the register values for band switch somehow get overwritten in the 
process.  I am told a fix is in the works for this.

-Walter