mfd: cpcap: Fix interrupt regression with regmap clear_ack

With commit 3a6f0fb7b8eb ("regmap: irq: Add support to clear ack
registers"), the cpcap interrupts are no longer getting acked properly
leading to a very unresponsive device with CPUs fully loaded spinning
in the threaded IRQ handlers.

To me it looks like the clear_ack commit above actually fixed a long
standing bug in regmap_irq_thread() where we unconditionally acked the
interrupts earlier without considering ack_invert. And the issue with
cpcap started happening as we now also consider ack_invert.

Tim Harvey <[e-mail]> tried to fix this issue earlier with
"[PATCH v2] regmap: irq: fix ack-invert", but the reading of the ack
register was considered unnecessary for just ack_invert, and we did not
have clear_ack available yet. As the cpcap irqs worked both with and
without ack_invert earlier because of the unconditional ack, the
problem remained hidden until now.

Also, looks like the earlier v3.0.8 based Motorola Android Linux kernel
does clear_ack style read-clear-write with "ireg_val & ~mreg_val" instead
of just ack_invert style write. So let's switch cpcap to use clear_ack
to fix the issue.

Fixes: 3a6f0fb7b8eb ("regmap: irq: Add support to clear ack registers")
Cc: Carl Philipp Klemm <[e-mail]>
Cc: Laxminath Kasam <[e-mail]>
Cc: Merlijn Wajer <[e-mail]>
Cc: Mark Brown <[e-mail]>
Cc: Pavel Machek <[e-mail]>
Cc: Sebastian Reichel <[e-mail]>
Cc: Tim Harvey <[e-mail]>
Signed-off-by: Tony Lindgren <[e-mail]>
Tested-by: Pavel Machek <[e-mail]>
Reviewed-By: Tim Harvey <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>

drivers/mfd/motorola-cpcap.c

···
 		.ack_base = CPCAP_REG_MI1,
 		.mask_base = CPCAP_REG_MIM1,
 		.use_ack = true,
-		.ack_invert = true,
+		.clear_ack = true,
 	},
 	{
 		.name = "cpcap-m2",
···
 		.ack_base = CPCAP_REG_MI2,
 		.mask_base = CPCAP_REG_MIM2,
 		.use_ack = true,
-		.ack_invert = true,
+		.clear_ack = true,
 	},
 	{
 		.name = "cpcap1-4",
···
 		.ack_base = CPCAP_REG_INT1,
 		.mask_base = CPCAP_REG_INTM1,
 		.use_ack = true,
-		.ack_invert = true,
+		.clear_ack = true,
 	},
 };