regmap-irq: Add no_status support

Some devices lack status registers, yet expect to handle interrupts.
Introduce a no_status flag to indicate such a configuration, where
rather than read a status register to verify, all interrupts received
are assumed to be active.

Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
Link: https://lore.kernel.org/r/bd501b4b5ff88da24d467f75e8c71b4e0e6f21e2.1677515341.git.william.gray@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>

include/linux/regmap.h

@@ -1567,6 +1567,7 @@ struct regmap_irq_chip_data;
  *		      the need for a @sub_reg_offsets table.
  * @status_invert: Inverted status register: cleared bits are active interrupts.
  * @runtime_pm:  Hold a runtime PM lock on the device when accessing it.
+ * @no_status: No status register: all interrupts assumed generated by device.
  *
  * @num_regs:    Number of registers in each control bank.
  * @irqs:        Descriptors for individual IRQs.  Interrupt numbers are
@@ -1631,6 +1632,7 @@ struct regmap_irq_chip {
 	unsigned int clear_on_unmask:1;
 	unsigned int not_fixed_stride:1;
 	unsigned int status_invert:1;
+	unsigned int no_status:1;
 
 	int num_regs;