Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/arch/powerpc/sysdev/ppc4xx_pci.h b/arch/powerpc/sysdev/ppc4xx_pci.h
index 56d9e5d..c39a134 100644
--- a/arch/powerpc/sysdev/ppc4xx_pci.h
+++ b/arch/powerpc/sysdev/ppc4xx_pci.h
@@ -324,7 +324,7 @@
 #define PESDR0_460EX_IHS2		0x036D
 
 /*
- * 460SX addtional DCRs
+ * 460SX additional DCRs
  */
 #define PESDRn_460SX_RCEI		0x02