video: tegra: host: remove unused code

video: tegra: host: remove unused code

remove below unused functions which were using memmgr
nvhost_cdma_push_gather()
push_buffer_push_to()

We have been using below new versions of above APIs
using iova/cpuva
_nvhost_cdma_push_gather()
_push_buffer_push_to()

Use new version everywhere and rename them again to
nvhost_cdma_push_gather()
push_buffer_push_to()

remove client_handle from push_buffer since we are no
longer using it

Bug 1450489

Change-Id: I24d1a602c0eabe1affb9fef3ff65a8ef5e960e2a
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/367621
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>