usb: cdnsp: Removes some not useful function arguments

This patch removes 'flags' argument from some functions and use
indirect the correct GFP_XXX flag to fix the following warning:

'The patch d40a169aab24: "usb: cdnsp: cdns3 Add main part of Cadence
USBSSP DRD Driver" from Dec 7, 2020, leads to the following static
checker warning:

	drivers/usb/cdns3/cdnsp-mem.c:1229 cdnsp_mem_init()
	warn: use 'flags' here instead of GFP_XXX?

drivers/usb/cdns3/cdnsp-mem.c
  1206  int cdnsp_mem_init(struct cdnsp_device *pdev, gfp_t flags);'
                                                      ^^^^^^^^^^^
Signed-off-by: Pawel Laszczak <pawell@cadence.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Peter Chen <peter.chen@nxp.com>