Chapter 27: "LPC43xx/LPC43Sxx USB API" of the LPC43xx user's manual states that the USB ROM API is only available for LPC4350/30/20 and LPC43S50/S30/S20 parts. However, the LPCOpen libraries and examples for LPC4370 include examples for usbd_rom_xxxxx. Please advise.
Let me answer my own question, after reading the code and cross checked using Google's search
Code:
By looking at the labtool/fw/Lib_USB/LPCUSBLIB/LPCUSBlibConfig.h
// Define USE_USB_ROM_STACK = 1 to use MCU's internal ROM stack, 0 if otherwise
#define USB_FORCED_FULLSPEED 0
Google's search
http://www.nxp-lpc.com/images/nxpUSBlib_v1_1.pdf
It is confirmed that LPC4370 does not support USB ROM API.