phy: mediatek: add a new helper to update bitfield

Due to FIELD_PREP() macro can be used to prepare a bitfield value,
local ones can be remove; add the new helper to make bitfield update
easier.

Signed-off-by: Chunfeng Yun <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/phy/mediatek/phy-mtk-io.h

···
 #ifndef __PHY_MTK_H__
 #define __PHY_MTK_H__
 
+#include <linux/bitfield.h>
 #include <linux/io.h>
 
 static inline void mtk_phy_clear_bits(void __iomem *reg, u32 bits)
···
 	tmp &= ~mask;
 	tmp |= val & mask;
 	writel(tmp, reg);
+}
+
+/* field @mask should be constant and continuous */
+static inline void mtk_phy_update_field(void __iomem *reg, u32 mask, u32 val)
+{
+	mtk_phy_update_bits(reg, mask, FIELD_PREP(mask, val));
 }
 
 #endif