MIPS: Remove dead define of ST_OFF

Commit 1a3d5957 ("MIPS: Tidy up FPU context switching") removed the
last usage of the macro ST_OFF. Remove the dead code.
Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: trivial@kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/15898/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/r4k_switch.S

@@ -25,12 +25,6 @@
 /* preprocessor replaces the fp in ".set fp=64" with $30 otherwise */
 #undef fp
 
-/*
- * Offset to the current process status flags, the first 32 bytes of the
- * stack are not used.
- */
-#define ST_OFF (_THREAD_SIZE - 32 - PT_SIZE + PT_STATUS)
-
 #ifndef USE_ALTERNATE_RESUME_IMPL
 /*
  * task_struct *resume(task_struct *prev, task_struct *next,