usb: host: tegra: code clean up

With this patch:
	1. Renamed structure and function names to be more meaningful.
	2. Removed unnecessary local variables.

Signed-off-by: Venu Byravarasu <vbyravarasu@nvidia.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>