[MIPS] Sparsemem fixes

1. MIPS should select SPARSEMEM_STATIC since allocating bootmem in
   memory_present() will corrupt bootmap area.
2. pfn_valid() for SPARSEMEM is defined in linux/mmzone.h
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

@@ -1694,6 +1694,7 @@ config ARCH_SPARSEMEM_ENABLE
 
 config ARCH_SPARSEMEM_ENABLE
 	bool
+	select SPARSEMEM_STATIC
 
 config NUMA
 	bool "NUMA Support"

include/asm-mips/page.h

@@ -138,16 +138,14 @@ typedef struct { unsigned long pgprot; } pgprot_t;
 
 #define pfn_to_kaddr(pfn)	__va((pfn) << PAGE_SHIFT)
 
-#ifndef CONFIG_SPARSEMEM
-#ifndef CONFIG_NEED_MULTIPLE_NODES
-#define pfn_valid(pfn)		((pfn) < max_mapnr)
-#endif
-#endif
-
 #ifdef CONFIG_FLATMEM
 
 #define pfn_valid(pfn)		((pfn) < max_mapnr)
 
+#elif defined(CONFIG_SPARSEMEM)
+
+/* pfn_valid is defined in linux/mmzone.h */
+
 #elif defined(CONFIG_NEED_MULTIPLE_NODES)
 
 #define pfn_valid(pfn)							\
@@ -159,8 +157,6 @@ typedef struct { unsigned long pgprot; } pgprot_t;
 	            : 0);						\
 })
 
-#else
-#error Provide a definition of pfn_valid
 #endif
 
 #define virt_to_page(kaddr)	pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)