USB: c67x00: remove redundant pointer urbp

Pointer urbp is assigned but is never read, hence it is redundant
and can be removed. Cleans up clang warning:

drivers/usb/c67x00/c67x00-sched.c:975:2: warning: Value stored to 'urbp'
is never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>