Add language switch key only to the phone layouts

java/res/drawable-hdpi/sym_keyboard_language_switch.png

java/res/drawable-mdpi/sym_keyboard_language_switch.png

java/res/values/attrs.xml

java/res/values/keyboard-icons-black.xml

java/res/values/keyboard-icons-ics.xml

java/res/values/keyboard-icons-white.xml

java/res/values/keycodes.xml

java/res/values/strings.xml

java/res/xml/key_styles_common.xml

java/res/xml/prefs.xml

java/res/xml/row_qwerty4.xml

...d/inputmethod/compat/InputMethodManagerCompatWrapper.java

java/src/com/android/inputmethod/keyboard/Keyboard.java

java/src/com/android/inputmethod/keyboard/KeyboardId.java

java/src/com/android/inputmethod/keyboard/KeyboardSet.java

...rc/com/android/inputmethod/keyboard/KeyboardSwitcher.java

...c/com/android/inputmethod/keyboard/LatinKeyboardView.java

...droid/inputmethod/keyboard/internal/KeyboardIconsSet.java

java/src/com/android/inputmethod/latin/LatinIME.java

java/src/com/android/inputmethod/latin/Settings.java