hw/arm: Express dependencies of the musca machines with Kconfig

Dependencies have been determined with trial-and-error and by
looking at the musca.c source file.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

hw/arm/Kconfig

@@ -75,6 +75,12 @@ config MAINSTONE
     select PFLASH_CFI01
     select SMC91C111
 
+config MUSCA
+    bool
+    select ARMSSE
+    select PL011
+    select PL031
+
 config MUSICPAL
     bool
     select BITBANG_I2C
@@ -427,6 +433,3 @@ config ARMSSE_CPUID
 
 config ARMSSE_MHU
     bool
-
-config MUSCA
-    bool