msm: pcie: Use SVS freq for pipe clock

PCIe HW supports Gen1 speed when pipe clock is set to SVS freq.
Thus, change the pipe clock freq to SVS freq which meets both
power saving and throughput requirements.

Change-Id: Ic426e06c45fde779c161ed6ccacc4fa57ccb280a
Signed-off-by: Yan He <yanhe@codeaurora.org>