Backport gpio_is_valid() for gpiolib from linux-2.6.26
Index: linux-2.6.25.10/include/asm-generic/gpio.h
===================================================================
--- linux-2.6.25.10.orig/include/asm-generic/gpio.h	2008-07-03 05:46:47.000000000 +0200
+++ linux-2.6.25.10/include/asm-generic/gpio.h	2008-07-20 20:32:12.000000000 +0200
@@ -16,6 +16,12 @@
 #define ARCH_NR_GPIOS		256
 #endif
 
+static inline int gpio_is_valid(int number)
+{
+	/* only some non-negative numbers are valid */
+	return ((unsigned)number) < ARCH_NR_GPIOS;
+}
+
 struct seq_file;
 
 /**