xen/arm: domain_build: Check return code of domain_vpl011_init

We are assigning return code of domain_vpl011_init() to a variable
without checking it for an error. Fix it.

Fixes: 3580c8b2df ("xen/arm: if direct-map domain use native UART address and IRQ number for vPL011")
Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>
Acked-by: Julien Grall <jgrall@amazon.com>

xen/arch/arm/domain_build.c

@@ -3826,7 +3826,11 @@ static int __init construct_domU(struct domain *d,
      * shall be done first.
      */
     if ( kinfo.vpl011 )
+    {
         rc = domain_vpl011_init(d, NULL);
+        if ( rc < 0 )
+            return rc;
+    }
 
     rc = prepare_dtb_domU(d, &kinfo);
     if ( rc < 0 )