RISC-V: Provide pgtable_l5_enabled on rv32

A few of the other page table level helpers are defined on rv32, but not
pgtable_l5_enabled.  This adds the definition as a constant and converts
pgtable_l4_enabled to a constant as well.

Link: https://lore.kernel.org/r/20230830044129.11481-2-palmer@rivosinc.comSigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/include/asm/pgtable-32.h

@@ -33,4 +33,7 @@
 					  _PAGE_WRITE | _PAGE_EXEC |	\
 					  _PAGE_USER | _PAGE_GLOBAL))
 
+static const __maybe_unused int pgtable_l4_enabled;
+static const __maybe_unused int pgtable_l5_enabled;
+
 #endif /* _ASM_RISCV_PGTABLE_32_H */

arch/riscv/include/asm/pgtable.h

@@ -914,7 +914,6 @@ extern uintptr_t _dtb_early_pa;
 #define dtb_early_pa	_dtb_early_pa
 #endif /* CONFIG_XIP_KERNEL */
 extern u64 satp_mode;
-extern bool pgtable_l4_enabled;
 
 void paging_init(void);
 void misc_mem_init(void);

arch/riscv/mm/init.c

@@ -49,10 +49,12 @@ u64 satp_mode __ro_after_init = SATP_MODE_32;
 #endif
 EXPORT_SYMBOL(satp_mode);
 
+#ifdef CONFIG_64BIT
 bool pgtable_l4_enabled = IS_ENABLED(CONFIG_64BIT) && !IS_ENABLED(CONFIG_XIP_KERNEL);
 bool pgtable_l5_enabled = IS_ENABLED(CONFIG_64BIT) && !IS_ENABLED(CONFIG_XIP_KERNEL);
 EXPORT_SYMBOL(pgtable_l4_enabled);
 EXPORT_SYMBOL(pgtable_l5_enabled);
+#endif
 
 phys_addr_t phys_ram_base __ro_after_init;
 EXPORT_SYMBOL(phys_ram_base);