wlcore: add debugfs macro to help print fw statistics arrays

Add a macro to make it easy to print arrays from the FW statistics
array in debugfs.  At the same time, increase the buffer size so
arrays fit more easily.

Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>