Input: lpc32xx_ts - check for clk_prepare_enable() error

clk_prepare_enable() may fail, so we better check its return value and
propagate it in the case of error.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>