unified: Remove unused K_PIPE_SIZE() macro

Change-Id: If7d3a0c9153365222c85072e62a537317b998bdb
Signed-off-by: Peter Mitsis <peter.mitsis@windriver.com>
diff --git a/include/kernel.h b/include/kernel.h
index 63e903a..ca8b143 100644
--- a/include/kernel.h
+++ b/include/kernel.h
@@ -937,8 +937,6 @@
 	struct k_pipe name =                                  \
 		K_PIPE_INITIALIZER(name, pipe_buffer_size, _k_pipe_buf_##name)
 
-#define K_PIPE_SIZE(buffer_size) (sizeof(struct k_pipe) + buffer_size)
-
 /**
  * @brief Runtime initialization of a pipe
  *