Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/drivers/dma/mpc512x_dma.c b/drivers/dma/mpc512x_dma.c
index 4f95d31..b9bae94 100644
--- a/drivers/dma/mpc512x_dma.c
+++ b/drivers/dma/mpc512x_dma.c
@@ -328,7 +328,7 @@
 	return IRQ_HANDLED;
 }
 
-/* proccess completed descriptors */
+/* process completed descriptors */
 static void mpc_dma_process_completed(struct mpc_dma *mdma)
 {
 	dma_cookie_t last_cookie = 0;