[IA64-SGI] pcdp: add PCDP pci interface support

Resend 2 with changes per Bjorn Helgaas comments.  Changes from original:

+ Change globals to vga_console_iobase/vga_console_membase and make them
  unconditional.
+ Address style-related comments.

Patch to extend the PCDP vga setup code to support PCI io/mem translations
for the legacy vga ioport and ram spaces on architectures (e.g. altix) which
need them.

Summary of the changes:

drivers/firmware/pcdp.c
drivers/firmware/pcdp.h
-----------------------
+ add declaration for the spec-defined PCI interface struct (pcdp_if_pci)
  as well as support macros.

+ extend setup_vga_console() to know about pcdp_if_pci and add a couple of
  globals to hold the io and mem translation offsets if present.

arch/ia64/kernel/setup.c
------------------------
+ tweek early_console_setup() to allow multiple early console setup routines
  to be called.

include/asm-ia64/vga.h
----------------------
+ make VGA_MAP_MEM vga_console_membase aware

Signed-off-by: Mark Maule <maule@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/kernel/setup.c

@@ -72,6 +72,8 @@ DEFINE_PER_CPU(unsigned long, ia64_phys_stacked_size_p8);
 unsigned long ia64_cycles_per_usec;
 struct ia64_boot_param *ia64_boot_param;
 struct screen_info screen_info;
+unsigned long vga_console_iobase;
+unsigned long vga_console_membase;
 
 unsigned long ia64_max_cacheline_size;
 unsigned long ia64_iobase;	/* virtual address for I/O accesses */
@@ -273,23 +275,25 @@ io_port_init (void)
 static inline int __init
 early_console_setup (char *cmdline)
 {
+	int earlycons = 0;
+
 #ifdef CONFIG_SERIAL_SGI_L1_CONSOLE
 	{
 		extern int sn_serial_console_early_setup(void);
 		if (!sn_serial_console_early_setup())
-			return 0;
+			earlycons++;
 	}
 #endif
 #ifdef CONFIG_EFI_PCDP
 	if (!efi_setup_pcdp_console(cmdline))
-		return 0;
+		earlycons++;
 #endif
 #ifdef CONFIG_SERIAL_8250_CONSOLE
 	if (!early_serial_console_init(cmdline))
-		return 0;
+		earlycons++;
 #endif
 
-	return -1;
+	return (earlycons) ? 0 : -1;
 }
 
 static inline void