video: tegra: nvmap: Remove old ZP support

video: tegra: nvmap: Remove old ZP support

Remove the old foreground page zeroing support. This is replaced
by using the background zeroed page pool support instead. If page
pools are empty clearing happens in the allocation context.

Bug 1371433
Bug 1392833

Change-Id: I2345455112ffe046b2b4282b552522d81e53ec70
Reviewed-on: http://git-master/r/383931
Signed-off-by: Jon McCaffrey <jmccaffrey@nvidia.com>
Reviewed-on: http://git-master/r/555611
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Alex Waterman <alexw@nvidia.com>
Reviewed-by: Mitch Luban <mluban@nvidia.com>