usb_dw_dc: Cleanup: write DIEPCTL register just once
usb_dw_dc: Cleanup: write DIEPCTL register just once

The enable and clear NAK bit can be legally written together, do it in
just one write.

Signed-off-by: Andy Ross <c70f9a6bf6ee0cd69c8af4ce5e6b131945769315@intel.com>

mbolivar/zephyr,galak/zephyr,aceofall/zephyr-iotos,ldts/zephyr,kraj/zephyr,zephyriot/zephyr,fbsder/zephyr,mbolivar/zephyr,mbolivar/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,zephyriot/zephyr,nashif/zephyr,aceofall/zephyr-iotos,aceofall/zephyr-iotos,fbsder/zephyr,nashif/zephyr,galak/zephyr,kraj/zephyr,Vudentz/zephyr,Vudentz/zephyr,kraj/zephyr,finikorg/zephyr,nashif/zephyr,punitvara/zephyr,fbsder/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,zephyriot/zephyr,fbsder/zephyr,Vudentz/zephyr,nashif/zephyr,zephyriot/zephyr,explora26/zephyr,punitvara/zephyr,ldts/zephyr,Vudentz/zephyr,zephyriot/zephyr,ldts/zephyr,explora26/zephyr,explora26/zephyr,aceofall/zephyr-iotos,punitvara/zephyr,explora26/zephyr,mbolivar/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,galak/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,aceofall/zephyr-iotos,zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,explora26/zephyr,punitvara/zephyr,finikorg/zephyr,galak/zephyr,kraj/zephyr,kraj/zephyr,fbsder/zephyr,mbolivar/zephyr,punitvara/zephyr,ldts/zephyr