arm/tegra: pcie: fix return value of function

In previous patch (arm/tegra: add timeout to PCIe PLL lock detection loop)
tegra_pcie_enable_controller() function type has been changed from
void to int, but the last return statement wasn't converted, so
function returns undefined value. Fix it.

Also while at it, address couple of minor concerns raised by reviewers:
use usleep_range for delay, and lower the value of timeout to 300ms
to be consistent with Nvidia Vibrante kernel.

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