arm/mpu: Enable is_xen_heap_page and is_xen_heap_mfn for ARM_32

In case of ARM_32, all of the RAM will be covered by a permanent contiguous
mapping (where VA == PA) and there will be a single heap. Thus, the memory
allocated from Xen heap uses PGC_xen_heap.
This is similar to the scenario described for
"CONFIG_SEPARATE_XENHEAP=n W/ DIRECT MAP OF ALL RAM" in common/page_alloc.c.

Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com>
Reviewed-by: Hari Limaye <hari.limaye@arm.com>
Tested-by: Hari Limaye <hari.limaye@arm.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>

xen/arch/arm/include/asm/mm.h

@@ -170,7 +170,7 @@ struct page_info
 #define _PGC_need_scrub   _PGC_allocated
 #define PGC_need_scrub    PGC_allocated
 
-#ifdef CONFIG_ARM_64
+#if defined(CONFIG_ARM_64) || defined(CONFIG_MPU)
 #define is_xen_heap_page(page) ((page)->count_info & PGC_xen_heap)
 #define is_xen_heap_mfn(mfn) \
     (mfn_valid(mfn) && is_xen_heap_page(mfn_to_page(mfn)))

xen/arch/arm/include/asm/mpu/mm.h

@@ -27,11 +27,6 @@ extern pr_t xen_mpumap[MAX_MPU_REGION_NR];
 
 #define virt_to_maddr(va) ((paddr_t)((vaddr_t)(va) & PADDR_MASK))
 
-#ifdef CONFIG_ARM_32
-#define is_xen_heap_page(page) ({ BUG_ON("unimplemented"); false; })
-#define is_xen_heap_mfn(mfn) ({ BUG_ON("unimplemented"); false; })
-#endif
-
 /* On MPU systems there is no translation, ma == va. */
 static inline void *maddr_to_virt(paddr_t ma)
 {