[PATCH] _test_generic_punch: Extend $testfile's size to work with 64k block.

[chandan]

Hello Dave,

> So, to do this properly, I'd suggest that the code needs to scale
> the offset/size of the IO being done by the filesystem block size,
> not use a fixed size. Using a filter on the bmap output to handle
> the different block ranges will ensure everything works correctly
> from a golden output POV, except for one thing - the md5sum.
> 
Yes, we did try the approach of using variable block size and scaling
the offset values in the filter function. But we got stuck
working with md5sum (since we would need two sets of md5sums (with and
without '-k' option) per block size). As suggested, I will be
reposting the patch to use "_requires_le_4k_blocksize".

chandan