iio: adc: nxp-sar-adc: harden buffer ISR against per-channel read failure

iio: adc: nxp-sar-adc: harden buffer ISR against per-channel read failure

nxp_sar_adc_isr_buffer() bails on the first channel-read failure
without calling iio_trigger_notify_done(), so the trigger use_count
is left incremented and iio_trigger_poll_chained() drops subsequent
dispatches until the device is rebound.

Reaching this path means a state machine has gone wrong (driver bug
or the SAR ADC in an unexpected state) rather than a transient bus
issue, so this is hardening rather than a bug fix. If the underlying
condition persists the device is wedged and needs an unbind anyway.

Call iio_trigger_notify_done() on the error exit too, matching the
success path. The nxp_sar_adc_read_notify() duplication is intentional
and avoids a goto label for a two-line bail-out, as suggested by David.

Signed-off-by: Stepan Ionichev <sozdayvek@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>