usb: chipidea: Reallocate regmap only if lpm is detected

The regmap only needs to reallocate if the hw_read on the CAP register shows
lpm is used. Therefore the if() statement check the change.

Signed-off-by: Chris Ruehl <chris.ruehl@gtsys.com.hk>
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>