xen/memory: make 'ioreq_server_max_frames' static

The function 'ioreq_server_max_frames' can be defined static,
as its only uses are within the same file. This in turn avoids
violating MISRA C:2012 Rule 8.4 because no declaration is present.

No functional change.

Fixes: 9244528955 ("xen/memory: Fix acquire_resource size semantics”)
Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>

xen/common/memory.c

@@ -1120,7 +1120,7 @@ static long xatp_permission_check(struct domain *d, unsigned int space)
     return xsm_add_to_physmap(XSM_TARGET, current->domain, d);
 }
 
-unsigned int ioreq_server_max_frames(const struct domain *d)
+static unsigned int ioreq_server_max_frames(const struct domain *d)
 {
     unsigned int nr = 0;