i40e: Fix for truncated interrupt name

This patch extends the size of the text available for the interrupt names.
Without this patch, all the descriptive data available for the Flow
Director interrupts is truncated.

Change-ID: I2ac458f23ac3b4ea8f1edf73edc283b1d3704c7f
Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>