USB: whci-hcd: add more checks for dma mapping error
Fixing checks for dma mapping error in qset_fill_page_list(),
I have missed two similar problems in qset_add_urb_sg() and
in qset_add_urb_sg_linearize().
v2: check validity of dma_addr with dma_mapping_error()
in qset_free_std() as suggested by Vladimir Zapolskiy.
Found by Linux Driver Verification project (linuxtesting.org).