Thermal: imx: add clk disable/enable for suspend/resume

Thermal sensor's clk is from pll3_usb_otg, per hardware
design requirement, need to make sure pll3_usb_otg is disabled
before STOP mode is entered, otherwise, all PFDs under it may
enter incorrect state, this patch disables pll3_usb_otg before
suspend and enables it after resume.

Signed-off-by: Anson Huang <b20788@freescale.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>