pci: Clean up PCI info when CONFIG_PCI_SCAN_SHOW

pci: Clean up PCI info when CONFIG_PCI_SCAN_SHOW

This change does the following:
- Removes the printing of the PCI interrupt line value.  This is
  normally set to 0 by U-Boot on bootup and is rarely used during
  everyday operation.

- Prints out the PCI function number of a device.  Previously a device
  with multiple functions would be printed identically 2 times, which is
  generally confusing.  For example, on an Intel 2 port gigabit Ethernet
  card the following was displayed:
    ...
    04  01  8086  1010  0200  00
    04  01  8086  1010  0200  00
    ...

- Prints a text description of each device's PCI class instead of the
  raw PCI class code.  The textual description makes it much easier to
  determine what devices are installed on a PCI bus.

- Changes the general formatting of the PCI device output.

Previous output:
  PCIE1: connected as Root Complex
          04  01  8086  1010  0200  00
          04  01  8086  1010  0200  00
          03  00  10b5  8112  0604  00
          02  01  10b5  8518  0604  00
          02  02  10b5  8518  0604  00
          08  00  1957  0040  0b20  00
          07  00  10b5  8518  0604  00
          09  00  10b5  8112  0604  00
          07  01  10b5  8518  0604  00
          07  02  10b5  8518  0604  00
          06  00  10b5  8518  0604  00
          02  03  10b5  8518  0604  00
          01  00  10b5  8518  0604  00
  PCIE1: Bus 00 - 0b
  PCIE2: connected as Root Complex
          0d  00  1957  0040  0b20  00
  PCIE2: Bus 0c - 0d

Updated output:
  PCIE1: connected as Root Complex
          04:01.0 - 8086:1010 - Network controller
          04:01.1 - 8086:1010 - Network controller
          03:00.0 - 10b5:8112 - Bridge device
          02:01.0 - 10b5:8518 - Bridge device
          02:02.0 - 10b5:8518 - Bridge device
          08:00.0 - 1957:0040 - Processor
          07:00.0 - 10b5:8518 - Bridge device
          09:00.0 - 10b5:8112 - Bridge device
          07:01.0 - 10b5:8518 - Bridge device
          07:02.0 - 10b5:8518 - Bridge device
          06:00.0 - 10b5:8518 - Bridge device
          02:03.0 - 10b5:8518 - Bridge device
          01:00.0 - 10b5:8518 - Bridge device
  PCIE1: Bus 00 - 0b
  PCIE2: connected as Root Complex
          0d:00.0 - 1957:0040 - Processor
  PCIE2: Bus 0c - 0d

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>