fix(drivers/usb): fix Null pointer dereferences in usb_core_set_config

Correct the invalid test on NULL pointer pdev->class in
usb_core_set_config function.

This patch fix the coverity errors:

  ** CID 373790:  Null pointer dereferences  (FORWARD_NULL)
  /drivers/usb/usb_device.c: 182 in usb_core_set_config()

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Change-Id: I83e43261bafa2d47f800e56df0b047a6c58a1e29
1 file changed