clk: at91: clk-master: fix prescaler logic

When prescaler value read from register is MASTER_PRES_MAX it means
that the input clock will be divided by 3. Fix the code to reflect
this.

Fixes: 7a110b91 ("clk: at91: clk-master: re-factor master clock")
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20211011112719.3951784-11-claudiu.beznea@microchip.comAcked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/at91/clk-master.c

@@ -386,7 +386,7 @@ static unsigned long clk_master_pres_recalc_rate(struct clk_hw *hw,
 
 	val &= master->layout->mask;
 	pres = (val >> master->layout->pres_shift) & MASTER_PRES_MASK;
-	if (pres == 3 && characteristics->have_div3_pres)
+	if (pres == MASTER_PRES_MAX && characteristics->have_div3_pres)
 		pres = 3;
 	else
 		pres = (1 << pres);