OmniGears: SeekBarPreference push min max values

Thanks to http://gerrit.dirtyunicorns.com/#/c/6600/

Change-Id: Id3eb1d83daf810b9076205b6fe5155d8d6e345d1
diff --git a/src/org/omnirom/omnigears/preference/SeekBarPreference.java b/src/org/omnirom/omnigears/preference/SeekBarPreference.java
index 117bca6..5dd88ee 100644
--- a/src/org/omnirom/omnigears/preference/SeekBarPreference.java
+++ b/src/org/omnirom/omnigears/preference/SeekBarPreference.java
@@ -189,10 +189,16 @@
 
     public void setMaxValue(int value) {
         mMaxValue = value;
+        if (mSeekBar != null) {
+            mSeekBar.setMax(mMaxValue - mMinValue);
+        }
     }
 
     public void setMinValue(int value) {
         mMinValue = value;
+        if (mSeekBar != null) {
+            mSeekBar.setMax(mMaxValue - mMinValue);
+        }
     }
 
     @Override