Moved map lookup outside of inner loop

This commit pulls a change that was made on the new multi-block reader
back to be the original reader from which the segment of code was copied.
The optimization is to move the map lookups getting the type and buffer
for the array outside of the inner loop that reads in the points.

Change-Id: I19973e962399db7753286accb335768926837c6c
Merge topic 'genericio_reader_optimization' into next

e708f49e Moved map lookup outside of inner loop