msm: pcie: optimize link training latency

The maximum link training latency allowed for PCIe endpoint is 100
ms. Check the link training status more frequently so that the
actual waiting time could be minimized when we enable PCIe link.

Change-Id: Ieb3f51ce35f670c0f95ec9b87d6ca2bd2e5d8d56
Signed-off-by: Yan He <yanhe@codeaurora.org>