Fix discard request map allocation

Discard handling splits large request into several steps.
However the actual size of request map for discard was
determined based on original request size, not step request
size, resulting in waste of memory and allocations > 4K.

Signed-off-by: Adam Rutkowski <adam.j.rutkowski@intel.com>

src/ocf_request.c

@@ -42,7 +42,7 @@ struct ocf_req_allocator {
 
 static inline size_t ocf_req_sizeof_map(struct ocf_request *req)
 {
-	uint32_t lines = req->alloc_core_line_count;
+	uint32_t lines = req->core_line_count;
 	size_t size = (lines * sizeof(struct ocf_map_info));
 
 	ENV_BUG_ON(lines == 0);