mips: sgi-ip27: switch from DISCONTIGMEM to SPARSEMEM

The memory initialization of SGI-IP27 is already half-way to support
SPARSEMEM. It only had free_bootmem_with_active_regions() left-overs
interfering with sparse_memory_present_with_active_regions().

Replace these calls with simpler memblocks_present() call in prom_meminit()
and adjust arch/mips/Kconfig to enable SPARSEMEM and SPARSEMEM_EXTREME for
SGI-IP27.
Co-developed-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

arch/mips/Kconfig

@@ -674,6 +674,7 @@ config SGI_IP22
 config SGI_IP27
 	bool "SGI IP27 (Origin200/2000)"
 	select ARCH_HAS_PHYS_TO_DMA
+	select ARCH_SPARSEMEM_ENABLE
 	select FW_ARC
 	select FW_ARC64
 	select BOOT_ELF64
@@ -2618,18 +2619,9 @@ config ARCH_FLATMEM_ENABLE
 	def_bool y
 	depends on !NUMA && !CPU_LOONGSON2
 
-config ARCH_DISCONTIGMEM_ENABLE
-	bool
-	default y if SGI_IP27
-	help
-	  Say Y to support efficient handling of discontiguous physical memory,
-	  for architectures which are either NUMA (Non-Uniform Memory Access)
-	  or have huge holes in the physical address space for other reasons.
-	  See <file:Documentation/vm/numa.rst> for more.
-
 config ARCH_SPARSEMEM_ENABLE
 	bool
-	select SPARSEMEM_STATIC
+	select SPARSEMEM_STATIC if !SGI_IP27
 
 config NUMA
 	bool "NUMA Support"

arch/mips/sgi-ip27/ip27-memory.c

@@ -385,12 +385,8 @@ static void __init node_mem_init(nasid_t node)
 	slot_freepfn += PFN_UP(sizeof(struct pglist_data) +
 			       sizeof(struct hub_data));
 
-	free_bootmem_with_active_regions(node, end_pfn);
-
 	memblock_reserve(slot_firstpfn << PAGE_SHIFT,
 			 ((slot_freepfn - slot_firstpfn) << PAGE_SHIFT));
-
-	sparse_memory_present_with_active_regions(node);
 }
 
 /*
@@ -423,6 +419,8 @@ void __init prom_meminit(void)
 		}
 		__node_data[node] = &null_node;
 	}
+
+	memblocks_present();
 }
 
 void __init prom_free_prom_memory(void)