Use String8/16 c_str [media]

Bug: 295394788
Test: make checkbuild
Change-Id: I4ba5400f39c769bec59508525844f1daefe1d15c
diff --git a/drm/drmserver/DrmManagerService.cpp b/drm/drmserver/DrmManagerService.cpp
index c830c6e..98eba2a 100644
--- a/drm/drmserver/DrmManagerService.cpp
+++ b/drm/drmserver/DrmManagerService.cpp
@@ -373,7 +373,7 @@
         (void)args;
 #endif
     }
-    write(fd, result.string(), result.size());
+    write(fd, result.c_str(), result.size());
     return NO_ERROR;
 }