RTS: ADC read 'max_loops' reset per card

Previously in the adc read function, a slow card would lead to 'max_loops' dropping to 1 and staying there for future cards.
Fast ADCs read after slow ADCs would not have the output data properly decimated.

src/include/drv/iop_adc_functions.c

@@ -323,6 +323,7 @@ iop_adc_read( adcInfo_t* adcinfo, int cpuClk[] )
 
         // loops and max_loops are usually equal to UNDERSAMPLE, but on the first cycle
         // they loops may be less.
+        max_loops = UNDERSAMPLE;
         if(first_adc_read)
         {
             loops = UNDERSAMPLE - cdsPciModules.adcTimeShift[card];