qcacmn: cleanup FEATURE_HAL_DELAYED_REG_WRITE_V2 support

This FEATURE_HAL_DELAYED_REG_WRITE_V2 was added to fix the
Audio jank issue, but it could not resolve it completely,
so that was later fixed by existing delayed reg write
support with the help of SMP2P messages to communicate
with FW regarding PCIe link status. This code is not being
used, so removing it and cleaning up the redundant code.

Change-Id: Iada088e72a76b4c071c8a80ee945f36ac959670e
CRs-Fixed: 3056475