hw/core: Add a config switch for the "split-irq" device

The "split-irq" device is currently only used by machines that use
CONFIG_ARMSSE. Let's add a proper CONFIG_SPLIT_IRQ switch for this
so that it only gets compiled when we really need it.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190817101931.28386-7-thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
diff --git a/hw/arm/Kconfig b/hw/arm/Kconfig
index 849195c..6e24c73 100644
--- a/hw/arm/Kconfig
+++ b/hw/arm/Kconfig
@@ -81,6 +81,7 @@
     select ARMSSE
     select PL011
     select PL031
+    select SPLIT_IRQ
 
 config MUSICPAL
     bool
@@ -364,6 +365,7 @@
     select OR_IRQ
     select PL022    # Serial port
     select PL080    # DMA controller
+    select SPLIT_IRQ
 
 config FSL_IMX7
     bool
@@ -442,6 +444,7 @@
     select IOTKIT_SYSCTL
     select IOTKIT_SYSINFO
     select OR_IRQ
+    select SPLIT_IRQ
     select TZ_MPC
     select TZ_MSC
     select TZ_PPC