powerpc/configs/6xx: Switch CONFIG_USB_EHCI_FSL to =m
In commit ca07e1c1e4a6 ("drivers:usb:fsl:Make fsl ehci drv an
independent driver module"), CONFIG_USB_EHCI_FSL was switched from
built-in to modular. Update the defconfig.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Michael Ellerman