usb: host: tegra: re-arranging ehci functions

Re-arranged EHCI generic and tegra specific functions
into two separate groups for more readability.

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>