usb: ehci-mx6: Make regulator DM_REGULATOR dependent

Do the regulator related work only if the build has the DM_REGULATOR.

Signed-off-by: Abel Vesa <abel.vesa@nxp.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
1 file changed