Removed unused member.

Author: Daniel K. O. (dkosmari)

source/ButtonComboManager.h

@@ -73,5 +73,4 @@ class ButtonComboManager {
     std::array<uint32_t, 2> mVPADSuppressed{};
     std::array<ButtonTracker<uint16_t>, 7> mWPADCoreBtns;
     std::array<ButtonTracker<uint32_t>, 7> mWPADExtBtns;
-    std::array<uint8_t, 7> mWPADExtension{};
 };