OmniGears: extend fpc availability check

Change-Id: I430ff0c910141af7b1208e844d3b6cfa709b741a
diff --git a/src/org/omnirom/omnigears/ButtonSettings.java b/src/org/omnirom/omnigears/ButtonSettings.java
index 270f6e2..7cf8edb 100644
--- a/src/org/omnirom/omnigears/ButtonSettings.java
+++ b/src/org/omnirom/omnigears/ButtonSettings.java
@@ -159,7 +159,7 @@
 
         mFingerprintManager = (FingerprintManager) getActivity().getSystemService(Context.FINGERPRINT_SERVICE);
         mFingerprintVib = (SwitchPreference) findPreference(FINGERPRINT_VIB);
-        if (!mFingerprintManager.isHardwareDetected()){
+        if (mFingerprintManager == null || !mFingerprintManager.isHardwareDetected()){
             otherCategory.removePreference(mFingerprintVib);
         } else {
             mFingerprintVib.setChecked((Settings.System.getInt(getContentResolver(),