soc: qcom: smp2p: Add select IRQ_DOMAIN

Since we are using irq_domain_add_linear(), add a select on IRQ_DOMAIN.
This is needed in order to be able to remove the depends on ARCH_QCOM.

drivers/soc/qcom/smp2p.c: In function ‘qcom_smp2p_inbound_entry’:
drivers/soc/qcom/smp2p.c:317:18: error: implicit declaration of function
  ‘irq_domain_add_linear’
  entry->domain = irq_domain_add_linear(node, 32, &smp2p_irq_ops, entry);
                  ^~~~~~~~~~~~~~~~~~~~~
Signed-off-by: Niklas Cassel <niklas.cassel@linaro.org>
Reviewed-by: Vivek Gautam <vivek.gautam@codeaurora.org>
Reviewed-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>

drivers/soc/qcom/Kconfig

@@ -134,6 +134,7 @@ config QCOM_SMP2P
 	depends on MAILBOX
 	depends on QCOM_SMEM
 	select QCOM_SMEM_STATE
+	select IRQ_DOMAIN
 	help
 	  Say yes here to support the Qualcomm Shared Memory Point to Point
 	  protocol.