Turn on PHY support for low speed

k66_usbhost.ino

 	print("init USBHS PHY & PLL");
 	// init process: page 1681-1682
 	USBPHY_CTRL_CLR = (USBPHY_CTRL_SFTRST | USBPHY_CTRL_CLKGATE); // // CTRL pg 1698
+	USBPHY_CTRL_SET = USBPHY_CTRL_ENUTMILEVEL2 | USBPHY_CTRL_ENUTMILEVEL3;
 	USBPHY_TRIM_OVERRIDE_EN_SET = 1;
 	USBPHY_PLL_SIC = USBPHY_PLL_SIC_PLL_POWER | USBPHY_PLL_SIC_PLL_ENABLE |
 		USBPHY_PLL_SIC_PLL_DIV_SEL(1) | USBPHY_PLL_SIC_PLL_EN_USB_CLKS;