genirq: Remove irq_chip_regs:: Polarity

The polarity member of struct irq_chip_regs is unused. Remove it along
with its kernel-doc.

Found by https://github.com/jirislaby/clang-struct.

Signed-off-by: Jiri Slaby (SUSE) <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Link: https://lore.kernel.org/all/[e-mail]

include/linux/irq.h

···
  * @ack:	Ack register offset to reg_base
  * @eoi:	Eoi register offset to reg_base
  * @type:	Type configuration register offset to reg_base
- * @polarity:	Polarity configuration register offset to reg_base
  */
 struct irq_chip_regs {
 	unsigned long		enable;
···
 	unsigned long		ack;
 	unsigned long		eoi;
 	unsigned long		type;
-	unsigned long		polarity;
 };
 
 /**