settings(embedis): missing condition for commit()

previous write() impl relied on comparing values before and after
assume that operations resulting in commit() are always written

code/espurna/settings.h

@@ -81,6 +81,7 @@ public:
     }
 
     void commit() const {
+        _instance->setDirty();
         autosaveSettings();
     }
 

code/espurna/storage_eeprom.h

@@ -30,6 +30,10 @@ public:
         return _data;
     }
 
+    void setDirty() {
+        _dirty = true;
+    }
+
     // fill all of the available storage with the 'value'
     void fill(uint8_t);