intel_adsp: ace: Fix function return

zephyr/soc/xtensa/intel_adsp/ace_v1x/irq.c: In function
'z_soc_irq_is_enabled':

zephyr/soc/xtensa/intel_adsp/ace_v1x/irq.c:47:3: warning: 'return'
with no value, in function returning non-void [-Wreturn-type]

   47 |   return;

Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>