trivial: Fix misspelling of firmware

Fix misspelling of firmware.

Signed-off-by: Nick Andrew <nick@nick-andrew.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/net/sb1250-mac.c b/drivers/net/sb1250-mac.c
index 88dd2e0..ce7551e 100644
--- a/drivers/net/sb1250-mac.c
+++ b/drivers/net/sb1250-mac.c
@@ -2299,7 +2299,7 @@
 	eaddr = sc->sbm_hwaddr;
 
 	/*
-	 * Read the ethernet address.  The firwmare left this programmed
+	 * Read the ethernet address.  The firmware left this programmed
 	 * for us in the ethernet address register for each mac.
 	 */