usb: phy: tegra: Remove unused functions

tegra_ehci_phy_restore_start() and tegra_ehci_phy_restore_end()
last use was removed in 2013 by
commit a4faa54e ("USB: EHCI: tegra: remove all power management")

tegra_usb_phy_preresume() and tegra_usb_phy_postresume() last
use was removed in 2020 by
commit c3590c76 ("usb: host: ehci-tegra: Remove the driver")
(Although that one makes me wonder how much of the rest of the file
is actually used)

Remove both sets.

Signed-off-by: "Dr. David Alan Gilbert" <linux@treblig.org>
Link: https://lore.kernel.org/r/20250603203905.279307-1-linux@treblig.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>