regmap: add a new macro:REGMAP_IRQ_REG_LINE(_id, _reg_bits)

if there are lots of irqs for a device and the register addresses for these
irqs is continuous, we can use this macro to initialize regmap_irq value.
Signed-off-by: Tony Xie <tony.xie@rock-chips.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

include/linux/regmap.h

@@ -1110,6 +1110,12 @@ struct regmap_irq {
 #define REGMAP_IRQ_REG(_irq, _off, _mask)		\
 	[_irq] = { .reg_offset = (_off), .mask = (_mask) }
 
+#define REGMAP_IRQ_REG_LINE(_id, _reg_bits) \
+	[_id] = {				\
+		.mask = BIT((_id) % (_reg_bits)),	\
+		.reg_offset = (_id) / (_reg_bits),	\
+	}
+
 /**
  * struct regmap_irq_chip - Description of a generic regmap irq_chip.
  *