ARM: OMAP2+: Fix config name for USB3 PHY

commit a70143 (drivers: phy: usb3/pipe3: Adapt pipe3 driver to Generic PHY
Framework) moved phy-omap-usb3 driver in drivers/usb/phy to drivers/phy and
also renamed the file to phy-ti-pipe3. It also renamed the config from
OMAP_USB3 to TI_PIPE3 in Kconfig. However the config name was not changed in
omap2plus_defconfig. Fixed it here.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>