Correct the jc index when print out the nest grid corner locations

[BinLiu-NOAA]

Description

This PR fixes a typo/bug when printing out the nest grid corner locations in tools/fv_grid_tools.F90.

Fixes #333

How Has This Been Tested? The fix has been tested in the HAFS application with ufs-weather-model.

Checklist:

Please check all whether they apply or not

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] Any dependent changes have been merged and published in downstream modules