Since non PVQ path in av1_encode_block_intra() was refactored
in nextgenv2 so that both inter and intra block txfm_quant,
i.e. av1_encode_block() and av1_encode_block_intra(), are done
similar way, such as both call av1_xform_quant().
This is also nice for PVQ, since it can reuse pvq enc helper call
in av1_xform_quant() for intra block mode.

Change-Id: I45aaf5b899552bf947d777cdb2d92e665d4f217e