clk: fractional-divider: keep mwidth and nwidth internally

The patch adds mwidth and nwidth fields to the struct clk_fractional_divider
for further usage. While here, use GENMASK() instead of open coding this
functionality.

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

include/linux/clk-provider.h

@@ -500,13 +500,14 @@ struct clk *clk_register_fixed_factor(struct device *dev, const char *name,
  *
  * Clock with adjustable fractional divider affecting its output frequency.
  */
-
 struct clk_fractional_divider {
 	struct clk_hw	hw;
 	void __iomem	*reg;
 	u8		mshift;
+	u8		mwidth;
 	u32		mmask;
 	u8		nshift;
+	u8		nwidth;
 	u32		nmask;
 	u8		flags;
 	spinlock_t	*lock;