Switch to exfatprogs compatible fsck parameter

exfatprogs accepts 'y' for no interaction repair.

Change-Id: I2c436816a293a36fc9f0cd635cdb9ca3b5f88bfc

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("-a");
+    cmd.push_back("-y");
     cmd.push_back(source);
 
     int rc = ForkExecvp(cmd, nullptr, sFsckUntrustedContext);