phy: lpc18xx-usb-otg: error handling in lpc18xx_usb_otg_phy_power_on()

If regmap_update_bits() fails in lpc18xx_usb_otg_phy_power_on(),
lpc->clk is left enabled.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>