rtc: max77686: Fix wake-ups for max77620

Following commit d8f090db ("rtc: max77686: Do not allow interrupt to
fire before system resume"), RTC wake-ups stopped working on Jetson TX2
and Jetson Xavier platforms. The Jetson TX2 uses the max77620 PMIC and
the Jetson Xavier uses max20024 PMIC. Both of these PMICs have the same
max77620 RTC controller.

For the max77620 RTC, the variable 'rtc_irq_from_platform' is defined as
true in the max77686 driver and because of this the IRQ passed to the
max77686 driver for RTC is the PMIC IRQ and not the parent. Hence,
following commit d8f090db ("rtc: max77686: Do not allow interrupt to
fire before system resume"), for the max77620 the RTC IRQ within the
PMIC is now getting disabled on entry to suspend and unable to wake the
system up. Fix this by only disabling interrupts on entry to suspend
in the max77686 RTC driver, if the interrupt is the parent interrupt.

Fixes: d8f090db ("rtc: max77686: Do not allow interrupt to fire before system resume")
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Tested-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20200806125431.699339-1-jonathanh@nvidia.com