tlb: arch: Remove empty __tlb_remove_tlb_entry() stubs

If __tlb_remove_tlb_entry() is not defined by the architecture then
we provide an empty definition in asm-generic/tlb.h.

Remove the redundant empty definitions for sparc64 and x86.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Yu Zhao <yuzhao@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lkml.kernel.org/r/20210127235347.1402-6-will@kernel.org