PCI: Revert aeb30016 ("PCI: add Intel USB specific reset method")

Revert aeb30016 ("PCI: add Intel USB specific reset method").

We checked for "dev->class == PCI_CLASS_SERIAL_USB", but dev->class
contains the entire three-byte base class/sub-class/interface, while
PCI_CLASS_SERIAL_USB is only the two-byte base class/sub-class.

This error meant that we used the Intel device-specific reset on devices
with class code 0x000c03 instead of those with class code 0x0c03xx.
0x000c03 is a reserved value in the 0x00 backwards compatibility base
class and shouldn't match any devices, so I think reset_intel_generic_dev()
always failed.

I considered adding a shift, but I can't test it, so it's as likely to
break something as to fix something.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Yu Zhao <yu.zhao@intel.com>
CC: Mathias Nyman <mathias.nyman@intel.com>