Fixed a misplaced ifdef that prevented npx.c building without "device isa"

ISA.  npx has few isa dependencies, but it does unconditional outb()'s to
the isa bus in the !SMP case, and it attaches to isa if "device isa" is
configured in order to support PNP-ISA.  The ifdef for the latter was
misplaced.

PR:		62595

sys/i386/isa/npx.c

@@ -1037,13 +1037,13 @@ static driver_t npx_driver = {
 
 static devclass_t npx_devclass;
 
-#ifdef DEV_ISA
 /*
  * We prefer to attach to the root nexus so that the usual case (exception 16)
  * doesn't describe the processor as being `on isa'.
  */
 DRIVER_MODULE(npx, nexus, npx_driver, npx_devclass, 0, 0);
 
+#ifdef DEV_ISA
 /*
  * This sucks up the legacy ISA support assignments from PNPBIOS/ACPI.
  */