add memory alignment for ARM32 (#4208) (#4401)

Co-authored-by: Daiki AMINAKA <1991.daiki@gmail.com>

Author: liveans

src/platform/datapath_epoll.c

@@ -76,7 +76,7 @@ typedef struct DATAPATH_RX_IO_BLOCK {
 
 } DATAPATH_RX_IO_BLOCK;
 
-typedef struct DATAPATH_RX_PACKET {
+typedef struct __attribute__((aligned(16))) DATAPATH_RX_PACKET {
     //
     // The IO block that owns the packet.
     //