arm/tegra: add timeout to PCIe PLL lock detection loop

Tegra PCIe driver waits for PLL to lock using busy loop.
If PLL fails to lock for some reason, this leads to silent lockup
while booting (as PCIe code is not modular).

Fix by adding timeout, so if PLL doesn't lock in a couple
of seconds, just PCIe driver fails and machine continues to boot.

Signed-off-by: Dmitry Artamonow <mad_soft@inbox.ru>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Olof Johansson <olof@lixom.net>