[Arith] Extend `DeduceBound` to handle `EQ` op

[umangyadav]

DeduceBound currently only works for the operators LT, GT, LE and GE.

It can be extended to handle EQ op with some checks.

DeduceBound at this point only seems to be used in one place that is in the LoopPartition.

With loop partition use-case consider the following example:

for (i, 0, 10) {
  select(likely((i == 5)), m, n)
}

On the TVM master branch currently, loop partition doesn't do anything on the above example and produces the same output as the input

However, with the EQ support in the deduce bound it can be partitioned to the following:

for (i, 0, 5) {
  n
}
m
for (i, 0, 4) {
  n
}

[tqchen]

Closed thanks to @umangyadav