Fix some obvious typos across multiple subsystems.

Typoes fixed:

  "partion" -> "partition"
  "retrive", "retreive" -> "retrieve"
  "th" -> "to"

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
diff --git a/common/cmd_mtdparts.c b/common/cmd_mtdparts.c
index 3023479..38a6e6d 100644
--- a/common/cmd_mtdparts.c
+++ b/common/cmd_mtdparts.c
@@ -420,7 +420,7 @@
 }
 
 /**
- * Delete selected partition from the partion list of the specified device.
+ * Delete selected partition from the partition list of the specified device.
  *
  * @param dev device to delete partition from
  * @param part partition to delete