usb_host: Don't build CDC host driver for unsupported targets

examples/peripherals/usb/host/cdc/common/cdc_acm_host/CMakeLists.txt

@@ -1,3 +1,15 @@
-idf_component_register(SRCS "cdc_acm_host.c"
+set(srcs)
-                    INCLUDE_DIRS "include"
+set(include)
-                    REQUIRES usb)
+# As CONFIG_USB_OTG_SUPPORTED comes from Kconfig, it is not evaluated yet
+# when components are being registered.
+set(require usb)
+
+if(CONFIG_USB_OTG_SUPPORTED)
+    list(APPEND srcs "cdc_acm_host.c")
+    list(APPEND include "include")
+endif()
+
+idf_component_register(SRCS ${srcs}
+                       INCLUDE_DIRS ${include}
+                       REQUIRES ${require}
+                       )