riscv: Fix compilation error with FAST_GUP and rv32

By surrounding the definition of pte_leaf_size() with a ifdef napot as
it should have been.

Fixes: e0fe5ab ("riscv: Fix pte_leaf_size() for NAPOT")
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Link: https://lore.kernel.org/r/20240304080247.387710-1-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Author: Alexandre Ghiti

arch/riscv/include/asm/pgtable.h

@@ -439,9 +439,11 @@ static inline pte_t pte_mkhuge(pte_t pte)
 	return pte;
 }
 
+#ifdef CONFIG_RISCV_ISA_SVNAPOT
 #define pte_leaf_size(pte)	(pte_napot(pte) ?				\
 					napot_cont_size(napot_cont_order(pte)) :\
 					PAGE_SIZE)
+#endif
 
 #ifdef CONFIG_NUMA_BALANCING
 /*