ARC: mm: tlb flush optim: elide redundant uTLB invalidates for MMUv3

For MMUv3 (and prior) the flush_tlb_{range,mm,page} API use the MMU
TLBWrite cmd which already nukes the entire uTLB, so NO need for
additional IVUTLB cmd from utlb_invalidate() - hence this patch

local_flush_tlb_all() is special since it uses a weaker TLBWriteNI
cmd (prec commit) to shoot down JTLB, hence we retain the explicit
uTLB flush

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>