Update src/pre_process/m_patches.fpp

Converted these iterators to integers.

Author: danieljvickers

src/pre_process/m_patches.fpp

@@ -256,7 +256,7 @@ contains
         gamma = fluid_pp(1)%gamma
         lit_gamma = (1._wp + gamma)/gamma
         j = 0
-        k = 0.0_wp
+        k = 0
 
         ! Transferring the line segment's centroid and length information
         x_centroid = patch_icpp(patch_id)%x_centroid