Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/include/linux/cfag12864b.h b/include/linux/cfag12864b.h
index 6f9f19d..b454dfc 100644
--- a/include/linux/cfag12864b.h
+++ b/include/linux/cfag12864b.h
@@ -44,7 +44,7 @@
 /*
  * Get the refresh rate of the LCD
  *
- * Returns the refresh rate (hertzs).
+ * Returns the refresh rate (hertz).
  */
 extern unsigned int cfag12864b_getrate(void);