USB: g_printer.h does not need to be "unifdef"ed.

Since the header file g_printer.h doesn't depend on __KERNEL__,
there's no need to unifdef it in the Kbuild file.
Signed-off-by: NRobert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

include/linux/usb/Kbuild

@@ -3,5 +3,5 @@ header-y += cdc.h
 header-y += ch9.h
 header-y += gadgetfs.h
 header-y += midi.h
-unifdef-y += g_printer.h
+header-y += g_printer.h