[MIPS] Remove unreferenced _IOC_SLMASK macro in ioctl.h.

Delete the definition of the apparently unreferenced macro _IOC_SLMASK.

Signed-off-by: Robert P. J. Day <[e-mail]>
Signed-off-by: Ralf Baechle <[e-mail]>

include/asm-mips/ioctl.h

···
 #define _IOC_DIRSHIFT	(_IOC_SIZESHIFT+_IOC_SIZEBITS)
 
 /*
- * We to additionally limit parameters to a maximum 255 bytes.
- */
-#define _IOC_SLMASK	0xff
-
-/*
  * Direction bits _IOC_NONE could be 0, but OSF/1 gives it a bit.
  * And this turns out useful to catch old ioctl numbers in header
  * files for us.