ARC: mm: tlb flush optim: elide repeated uTLB invalidate in loop

The unconditional full TLB flush (on say ASID rollover) iterates over each
entry and uses TLBWrite to zero it out. TLBWrite by design also invalidates
the uTLBs thus we end up invalidating it as many times as numbe rof
entries (512 or 1k)

Optimize this by using a weaker TLBWriteNI cmd in loop, which doesn't
tinker with uTLBs and an explicit one time IVUTLB, outside the loop to
invalidate them all once.

And given the optimiztion, the IVUTLB is now needed on MMUv4 too where
the uTLBs and JTLBs are otherwise coherent given the TLBInsertEntry /
TLBDeleteEntry commands

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