[TOPI] Initial NHWC layout support (#882)

* add 4 dim softmax

* update for NHWC layout

* remove layout param from softmax

* fix typo

* minor fix to pool

support axis=1 ndims=5 softmax.

add softmax axis

* few fix for softmax

* fix typo

* add more doc

* minor doc fix

* fix upsampling output shape

* fix lint

* cleanup softmax

* minor fix

* raise exception instead of assert, handles negative axis

* check axis after axis transformation