riscv: mm: fix 2 instances of -Wmissing-variable-declarations

I'm looking to enable -Wmissing-variable-declarations behind W=1. 0day
bot spotted the following instance in ARCH=riscv builds:

  arch/riscv/mm/init.c:276:7: warning: no previous extern declaration
  for non-static variable 'trampoline_pg_dir'
  [-Wmissing-variable-declarations]
  276 | pgd_t trampoline_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
      |       ^
  arch/riscv/mm/init.c:276:1: note: declare 'static' if the variable is
  not intended to be used outside of this translation unit
  276 | pgd_t trampoline_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
      | ^
  arch/riscv/mm/init.c:279:7: warning: no previous extern declaration
  for non-static variable 'early_pg_dir'
  [-Wmissing-variable-declarations]
  279 | pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
      |       ^
  arch/riscv/mm/init.c:279:1: note: declare 'static' if the variable is
  not intended to be used outside of this translation unit
  279 | pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
      | ^

These symbols are referenced by more than one translation unit, so make
sure they're both declared and include the correct header for their
declarations. Finally, sort the list of includes to help keep them tidy.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/llvm/202308081000.tTL1ElTr-lkp@intel.com/Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20230808-riscv_static-v2-1-2a1e2d2c7a4f@google.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/include/asm/pgtable.h

@@ -188,6 +188,8 @@ extern struct pt_alloc_ops pt_ops __initdata;
 #define PAGE_KERNEL_IO		__pgprot(_PAGE_IOREMAP)
 
 extern pgd_t swapper_pg_dir[];
+extern pgd_t trampoline_pg_dir[];
+extern pgd_t early_pg_dir[];
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 static inline int pmd_present(pmd_t pmd)

arch/riscv/mm/init.c

@@ -26,12 +26,13 @@
 #include <linux/kfence.h>
 
 #include <asm/fixmap.h>
-#include <asm/tlbflush.h>
-#include <asm/sections.h>
-#include <asm/soc.h>
 #include <asm/io.h>
-#include <asm/ptdump.h>
 #include <asm/numa.h>
+#include <asm/pgtable.h>
+#include <asm/ptdump.h>
+#include <asm/sections.h>
+#include <asm/soc.h>
+#include <asm/tlbflush.h>
 
 #include "../kernel/head.h"
 

arch/riscv/mm/kasan_init.c

@@ -22,7 +22,6 @@
  * region is not and then we have to go down to the PUD level.
  */
 
-extern pgd_t early_pg_dir[PTRS_PER_PGD];
 pgd_t tmp_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
 p4d_t tmp_p4d[PTRS_PER_P4D] __page_aligned_bss;
 pud_t tmp_pud[PTRS_PER_PUD] __page_aligned_bss;