Refactor use of iovec struct.

Use "struct iovec" instead of "iovec_t".
Prefix field names with iov_

Bug: 110161494
Change-Id: Ie47701231272a11dfabcd855f471382350472ec6
diff --git a/ipc/avb_ipc.cpp b/ipc/avb_ipc.cpp
index 32e066d..c8810f3 100644
--- a/ipc/avb_ipc.cpp
+++ b/ipc/avb_ipc.cpp
@@ -142,7 +142,7 @@
     }
     UniquePtr<uint8_t[]> msg_buf(new uint8_t[msg_info.len]);
 
-    iovec_t request_iov = {msg_buf.get(), msg_info.len};
+    struct iovec request_iov = {msg_buf.get(), msg_info.len};
     ipc_msg_t request_msg = {
             1,             // number of iovecs
             &request_iov,  // iovecs pointer
@@ -180,7 +180,7 @@
     // Send response message back to caller
     avb_message avb_response_header = {
             .cmd = avb_request_header->cmd | AVB_RESP_BIT, .result = error, {}};
-    iovec_t response_iov[2] = {
+    struct iovec response_iov[2] = {
             {&avb_response_header, sizeof(avb_response_header)},
             {out_buf.get(), out_size},
     };