iio: adc: palmas: Drop IRQF_EARLY_RESUME flag

Palmas gpadc IRQs are nested threaded and this flag is not required for nested
irqs anymore, since commit 3c646f2c ("genirq: Don't suspend nested_thread
irqs over system suspend") was merged.

Cc: Hartmut Knaack <knaack.h@gmx.de>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Peter Meerwald <pmeerw@pmeerw.net>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Nishanth Menon <nm@ti.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>