Kernel/File: Fixed file read/write hwtests

The 3DS allows the user to read from files opened with the Write access modifier, even if he did not specify the Read access modifier.

Open the files in binary mode so that we can prevent CR/LF problems in Windows, where a line-end is replaced by these two bytes instead of just 0xA, this was causing problems with the GetSize test

src/core/file_sys/file_sdmc.cpp

@@ -38,12 +38,15 @@ bool File_SDMC::Open() {
     }
 
     std::string mode_string;
-    if (mode.read_flag && mode.write_flag)
+    if (mode.create_flag)
         mode_string = "w+";
+    else if (mode.write_flag)
+        mode_string = "r+"; // Files opened with Write access can be read from
     else if (mode.read_flag)
         mode_string = "r";
-    else if (mode.write_flag)
-        mode_string = "w";
+    
+    // Open the file in binary mode, to avoid problems with CR/LF on Windows systems
+    mode_string += "b";
 
     file = new FileUtil::IOFile(path, mode_string.c_str());
     return true;