arm64: tlb: Remove redundant !CONFIG_HAVE_RCU_TABLE_FREE code

If there's one thing the RCU-based table freeing doesn't need, it's more
ifdeffery.

Remove the redundant !CONFIG_HAVE_RCU_TABLE_FREE code, since this option
is unconditionally selected in our Kconfig.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>