using AT91_PMC_MCKR_MDIV_ instead of LEGACY one in at91/clock.c

Signed-off-by: Asen Dimov <dimov@ronetix.at>
diff --git a/cpu/arm926ejs/at91/clock.c b/cpu/arm926ejs/at91/clock.c
index b06d760..ecf91f5 100644
--- a/cpu/arm926ejs/at91/clock.c
+++ b/cpu/arm926ejs/at91/clock.c
@@ -203,7 +203,8 @@
 	if (mckr & AT91_PMC_MCKR_MDIV_MASK)
 		freq /= 2;			/* processor clock division */
 #elif defined(CONFIG_AT91SAM9G45) || defined(CONFIG_AT91SAM9M10G45)
-	mck_rate_hz = (mckr & AT91_PMC_MCKR_MDIV_MASK) == AT91SAM9_PMC_MDIV_3
+	mck_rate_hz = (mckr & AT91_PMC_MCKR_MDIV_MASK) ==
+		(AT91_PMC_MCKR_MDIV_2 | AT91_PMC_MCKR_MDIV_4)
 		? freq / 3
 		: freq / (1 << ((mckr & AT91_PMC_MCKR_MDIV_MASK) >> 8));
 #else