irqdomain: Remove powerpc dependency from debugfs file

The debugfs code is really generic for all platforms.  This patch removes the
powerpc-specific directory reference and makes it available to all
architectures.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

kernel/irq/Kconfig

@@ -56,6 +56,16 @@ config GENERIC_IRQ_CHIP
 config IRQ_DOMAIN
 	bool
 
+config IRQ_DOMAIN_DEBUG
+	bool "Expose hardware/virtual IRQ mapping via debugfs"
+	depends on IRQ_DOMAIN && DEBUG_FS
+	help
+	  This option will show the mapping relationship between hardware irq
+	  numbers and Linux irq numbers. The mapping is exposed via debugfs
+	  in the file "virq_mapping".
+
+	  If you don't know what this means you don't need it.
+
 # Support forced irq threading
 config IRQ_FORCED_THREADING
        bool