wimax: export linux/wimax.h and linux/wimax/i2400m.h with headers_install

These two files are what user space can use to establish communication
with the WiMAX kernel API and to speak the Intel 2400m Wireless WiMAX
connection's control protocol.
Signed-off-by: NInaky Perez-Gonzalez <inaky@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

include/linux/Kbuild

@@ -371,3 +371,5 @@ unifdef-y += xattr.h
 unifdef-y += xfrm.h
 
 objhdr-y += version.h
+header-y += wimax.h
+header-y += wimax/

include/linux/wimax/Kbuild

+header-y += i2400m.h