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/mtd/xip.h b/include/linux/mtd/xip.h
index 36efcba..abed4de 100644
--- a/include/linux/mtd/xip.h
+++ b/include/linux/mtd/xip.h
@@ -51,7 +51,7 @@
  * 	return in usecs the elapsed timebetween now and the reference x as
  * 	returned by xip_currtime().
  *
- * 	note 1: convertion to usec can be approximated, as long as the
+ * 	note 1: conversion to usec can be approximated, as long as the
  * 		returned value is <= the real elapsed time.
  * 	note 2: this should be able to cope with a few seconds without
  * 		overflowing.