sh: intc: Fix up section mismatch for intc_ack_data

intc_ack_data is flagged as __init when it shouldn't be, causing section
mismatches in non-init paths like intc_set_ack_handle():

WARNING: drivers/built-in.o(.text+0x5d760):
Section mismatch in reference from the function
intc_set_ack_handle() to the function .init.text:intc_ack_data()
The function intc_set_ack_handle()
references the function __init intc_ack_data().
This is often because intc_set_ack_handle lacks a __init
annotation or the annotation of intc_ack_data is wrong.

Reported-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>