adb: clean up debug tracing a little.

Always use LOG() for debug tracing.
Remove useless D_lock. I believe it is useless to lock just before and after fprintf.

I verified the log output both on host and on device. The output looks fine to me.

Change-Id: I96ccfe408ff56864361551afe9ad464d197ae104
diff --git a/adb/adb_io.cpp b/adb/adb_io.cpp
index 7092609..14e295f 100644
--- a/adb/adb_io.cpp
+++ b/adb/adb_io.cpp
@@ -68,23 +68,23 @@
 
     size_t len0 = len;
 
-    D("readx: fd=%d wanted=%zu\n", fd, len);
+    D("readx: fd=%d wanted=%zu", fd, len);
     while (len > 0) {
         int r = adb_read(fd, p, len);
         if (r > 0) {
             len -= r;
             p += r;
         } else if (r == -1) {
-            D("readx: fd=%d error %d: %s\n", fd, errno, strerror(errno));
+            D("readx: fd=%d error %d: %s", fd, errno, strerror(errno));
             return false;
         } else {
-            D("readx: fd=%d disconnected\n", fd);
+            D("readx: fd=%d disconnected", fd);
             errno = 0;
             return false;
         }
     }
 
-    D("readx: fd=%d wanted=%zu got=%zu\n", fd, len0, len0 - len);
+    D("readx: fd=%d wanted=%zu got=%zu", fd, len0, len0 - len);
     if (ADB_TRACING) {
         dump_hex(reinterpret_cast<const unsigned char*>(buf), len0);
     }
@@ -104,12 +104,12 @@
     while (len > 0) {
         r = adb_write(fd, p, len);
         if (r == -1) {
-            D("writex: fd=%d error %d: %s\n", fd, errno, strerror(errno));
+            D("writex: fd=%d error %d: %s", fd, errno, strerror(errno));
             if (errno == EAGAIN) {
                 adb_sleep_ms(1); // just yield some cpu time
                 continue;
             } else if (errno == EPIPE) {
-                D("writex: fd=%d disconnected\n", fd);
+                D("writex: fd=%d disconnected", fd);
                 errno = 0;
                 return false;
             } else {