riscv: mm: make pmd_bad() check leaf condition

In the definition in Documentation/vm/arch_pgtable_helpers.rst,
pmd_bad() means test a non-table mapped PMD, so it should also
return true when it is a leaf page.
Signed-off-by: NNanyong Sun <sunnanyong@huawei.com>
Signed-off-by: NPalmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/include/asm/pgtable.h

@@ -184,7 +184,7 @@ static inline int pmd_none(pmd_t pmd)
 
 static inline int pmd_bad(pmd_t pmd)
 {
-	return !pmd_present(pmd);
+	return !pmd_present(pmd) || (pmd_val(pmd) & _PAGE_LEAF);
 }
 
 #define pmd_leaf	pmd_leaf