eal/ppc64: revert arch-specific TSC freq query

eal/ppc64: revert arch-specific TSC freq query

This reverts commit 15692396fd68932b6a81f00f12d4b0da12baa7d3
(eal/ppc64: implement arch-specific TSC freq query).
We intended to derive pkt/sec estimation with cpu clock frequency.
As timebase register serves the timer purpose, we need to stick with it
for calculating pkt/sec, hence reverting the change.

Fixes: 15692396fd ("eal/ppc64: implement arch-specific TSC freq query")
Cc: stable@dpdk.org
Signed-off-by: Gowrishankar Muthukrishnan <gowrishankar.m@linux.vnet.ibm.com>
Acked-by: Chao Zhu <chaozhu@linux.vnet.ibm.com>