tegra: usb: fix wrong error check

loop_count runs down from 10000, so the correct condition to error out
is ==0.

Signed-off-by: Lucas Stach <dev@lynxeye.de>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
CC: Stephen Warren <swarren@wwwdotorg.org>
CC: Tom Warren <twarren.nvidia@gmail.com>
Tested-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>