Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/Documentation/dell_rbu.txt b/Documentation/dell_rbu.txt
index 1517498..d262e22 100644
--- a/Documentation/dell_rbu.txt
+++ b/Documentation/dell_rbu.txt
@@ -62,7 +62,7 @@
 file.
 This file is then copied to /sys/class/firmware/dell_rbu/data.
 Once this file gets to the driver, the driver extracts packet_size data from
-the file and spreads it accross the physical memory in contiguous packet_sized
+the file and spreads it across the physical memory in contiguous packet_sized
 space.
 This method makes sure that all the packets get to the driver in a single operation.