dwc2: add dwc2_int_set to bcm, gd32 and xmc ports and build their host examples (#4100)

hcd_dwc2.c calls dwc2_int_set(), which these port headers lacked, so any host build failed as efm32 did in #4082. Their USB IRQs now dispatch by role via tusb_int_handler(). Admit broadcom_32bit, gd32vf103 and xmc4000 to the bare-metal host examples for build coverage; host is not yet validated on hardware. hcdma takes a uintptr_t cast like dcd_dwc2.c so broadcom_64bit compiles the host driver.