MIPS: ioctl.h: Fix headers_check warnings

Make ioctl.h compatible with asm-generic/ioctl.h and userspace

fix the following 'make headers_check' warning:

  usr/include/asm-mips/ioctl.h:64: extern's make no sense in userspace
Signed-off-by: NJaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/ioctl.h

@@ -60,12 +60,16 @@
 	 ((nr)   << _IOC_NRSHIFT) | \
 	 ((size) << _IOC_SIZESHIFT))
 
+#ifdef __KERNEL__
 /* provoke compile error for invalid uses of size argument */
 extern unsigned int __invalid_size_argument_for_IOC;
 #define _IOC_TYPECHECK(t) \
 	((sizeof(t) == sizeof(t[1]) && \
 	  sizeof(t) < (1 << _IOC_SIZEBITS)) ? \
 	  sizeof(t) : __invalid_size_argument_for_IOC)
+#else
+#define _IOC_TYPECHECK(t)	(sizeof(t))
+#endif
 
 /* used to create numbers */
 #define _IO(type, nr)		_IOC(_IOC_NONE, (type), (nr), 0)