logd: remove class LogCommand, rename LogCommand.cpp to LogPermissions.cpp

class LogCommand isn't needed, so remove it.  Since the rest of
LogCommand.cpp only has to do with permissions, rename it
appropriately.

Test: logging unit tests
Change-Id: I32d09c74d00b6e50083e46832eca3dd886b46682
diff --git a/logd/Android.bp b/logd/Android.bp
index ee86566..d203062 100644
--- a/logd/Android.bp
+++ b/logd/Android.bp
@@ -32,10 +32,10 @@
     name: "liblogd",
 
     srcs: [
-        "LogCommand.cpp",
         "ChattyLogBuffer.cpp",
         "CommandListener.cpp",
         "LogListener.cpp",
+        "LogPermissions.cpp",
         "LogReader.cpp",
         "LogReaderList.cpp",
         "LogReaderThread.cpp",