stm32f4xx_hal_pcd.c@346,22: unused variable 'ep'

Compiler warning fix, trivial. One function has an unused
variable, delete that line.

Author: Janne Kiiskila

targets/TARGET_STM/TARGET_STM32F4/device/stm32f4xx_hal_pcd.c

@@ -343,7 +343,6 @@ void HAL_PCD_IRQHandler(PCD_HandleTypeDef *hpcd)
   USB_OTG_GlobalTypeDef *USBx = hpcd->Instance;
   uint32_t i = 0U, ep_intr = 0U, epint = 0U, epnum = 0U;
   uint32_t fifoemptymsk = 0U, temp = 0U;
-  USB_OTG_EPTypeDef *ep;
   uint32_t hclk = 180000000U;
 
   /* ensure that we are in device mode */