asm-generic/tlb: stub out pud_free_tlb() if nopud ...

... independent of __ARCH_HAS_4LEVEL_HACK

This came up when removing __ARCH_HAS_5LEVEL_HACK for ARC as code bloat.
With this patch we see the following code reduction

| bloat-o-meter2 vmlinux-B-elide-ARCH_USE_5LEVEL_HACK vmlinux-C-elide-pud_free_tlb
| add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-104 (-104)
| function                                     old     new   delta
| free_pgd_range                               656     552    -104
| Total: Before=4137276, After=4137172, chg -1.000000%

Note: The primary change is alternate defintion for pud_free_tlb() but
while there also removed empty stubs for __pud_free_tlb, which is anyhow
called only from pud_free_tlb()

Link: http://lkml.kernel.org/r/20191016162400.14796-3-vgupta@synopsys.com
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Nick Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>