Revert "extmod: Place lwIP memory in a dedicated section."

This reverts commit 7d23620.

Author: iabdalkader

extmod/lwip-include/lwipopts_common.h

@@ -109,11 +109,6 @@
 // Needed for PPP.
 #define sys_jiffies sys_now
 
-// Place lwIP memory in a dedicated section to allow relocating it.
-// Note: alignment is enforced without adding trailing padding bytes.
-#define LWIP_DECLARE_MEMORY_ALIGNED(variable_name, size) \
-    __attribute__((section(".lwip"), aligned(MEM_ALIGNMENT))) u8_t variable_name[size]
-
 typedef uint32_t sys_prot_t;
 
 #endif // MICROPY_INCLUDED_LWIPOPTS_COMMON_H