arm64: Replace hard-coded values in the pmd/pud_bad() macros

This patch replaces the hard-coded value 2 with PMD_TABLE_BIT in the
pmd/pud_bad() macros. Note that using these macros on pmd_trans_huge()
entries is giving incorrect results
(pmd_none_or_trans_huge_or_clear_bad() correctly checks for
pmd_trans_huge before pmd_bad).

Additionally, white-space clean-up for pmd_mkclean().

Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>