libsel4utils: Missing vspace include

Adds a missing include from when the vspace code was changed to include arch includes
instead of directly including sel4_arch ones

libsel4utils/arch_include/arm/sel4utils/arch/vspace.h

diff --git a/libsel4utils/arch_include/arm/sel4utils/arch/vspace.h b/libsel4utils/arch_include/arm/sel4utils/arch/vspace.h
index e4e3986..5767e14 100644
--- a/libsel4utils/arch_include/arm/sel4utils/arch/vspace.h
+++ b/libsel4utils/arch_include/arm/sel4utils/arch/vspace.h
@@ -12,3 +12,4 @@
 #pragma once
 
 #include <sel4utils/sel4_arch/util.h>
+#include <sel4utils/sel4_arch/vspace.h>