Revert "Switch to exfatprogs compatible fsck parameter"

* While this is/will be correct in the long term
  support for ExFat, currently the tools aren't mature enough
  to forcelly try fixing all supported errors

* Go back to their "known" safe/working set

* Newer versions of exfatprogs added support for -a
  argument

This reverts commit bc2566c837.

Change-Id: I9c8e2b581002c59231cc36c0dce79715fe16238b

fs/Exfat.cpp

@@ -41,7 +41,7 @@ bool IsSupported() {
 status_t Check(const std::string& source) {
     std::vector<std::string> cmd;
     cmd.push_back(kFsckPath);
-    cmd.push_back("-y");
+    cmd.push_back("-a");
     cmd.push_back(source);
 
     int rc = ForkExecvp(cmd, nullptr, sFsckUntrustedContext);