Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/drivers/net/can/at91_can.c b/drivers/net/can/at91_can.c
index 57d2ffb..74efb5a 100644
--- a/drivers/net/can/at91_can.c
+++ b/drivers/net/can/at91_can.c
@@ -416,7 +416,7 @@
 
 	stats->tx_bytes += cf->can_dlc;
 
-	/* _NOTE_: substract AT91_MB_TX_FIRST offset from mb! */
+	/* _NOTE_: subtract AT91_MB_TX_FIRST offset from mb! */
 	can_put_echo_skb(skb, dev, mb - AT91_MB_TX_FIRST);
 
 	/*
@@ -782,7 +782,7 @@
 		reg_msr = at91_read(priv, AT91_MSR(mb));
 		if (likely(reg_msr & AT91_MSR_MRDY &&
 			   ~reg_msr & AT91_MSR_MABT)) {
-			/* _NOTE_: substract AT91_MB_TX_FIRST offset from mb! */
+			/* _NOTE_: subtract AT91_MB_TX_FIRST offset from mb! */
 			can_get_echo_skb(dev, mb - AT91_MB_TX_FIRST);
 			dev->stats.tx_packets++;
 		}