[PATCH] I2C: Clarify the usage of i2c-dev.h

Upon suggestion by Nils Roeder, here is an update to the i2c
documentation to clarify which header files user-space applications
relying on the i2c-dev interface should include.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Documentation/i2c/dev-interface

@@ -14,9 +14,12 @@ C example
 =========
 
 So let's say you want to access an i2c adapter from a C program. The
-first thing to do is `#include <linux/i2c.h>" and "#include <linux/i2c-dev.h>. 
-Yes, I know, you should never include kernel header files, but until glibc 
-knows about i2c, there is not much choice.
+first thing to do is "#include <linux/i2c-dev.h>". Please note that
+there are two files named "i2c-dev.h" out there, one is distributed
+with the Linux kernel and is meant to be included from kernel
+driver code, the other one is distributed with lm_sensors and is
+meant to be included from user-space programs. You obviously want
+the second one here.
 
 Now, you have to decide which adapter you want to access. You should
 inspect /sys/class/i2c-dev/ to decide this. Adapter numbers are assigned
@@ -78,7 +81,7 @@ Full interface description
 ==========================
 
 The following IOCTLs are defined and fully supported 
-(see also i2c-dev.h and i2c.h):
+(see also i2c-dev.h):
 
 ioctl(file,I2C_SLAVE,long addr)
   Change slave address. The address is passed in the 7 lower bits of the