x86/mmiotrace: uses/depends on PCI

Don't try to build mmiotrace when CONFIG_PCI=n.

next-20080416/kernel/trace/trace_mmiotrace.c: In function 'mmio_print_pcidev':
next-20080416/kernel/trace/trace_mmiotrace.c:62: error: implicit declaration of function 'pci_dev_driver'
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

arch/x86/Kconfig.debug

@@ -173,7 +173,7 @@ config MMIOTRACE_HOOKS
 
 config MMIOTRACE
 	bool "Memory mapped IO tracing"
-	depends on DEBUG_KERNEL
+	depends on DEBUG_KERNEL && PCI
 	select TRACING
 	select MMIOTRACE_HOOKS
 	default y
@@ -181,7 +181,7 @@ config MMIOTRACE
 	  Mmiotrace traces Memory Mapped I/O access and is meant for
 	  debugging and reverse engineering. It is called from the ioremap
 	  implementation and works via page faults. Tracing is disabled by
-	  default and can be enabled run-time.
+	  default and can be enabled at run-time.
 
 	  See Documentation/tracers/mmiotrace.txt.
 	  If you are not helping to develop drivers, say N.