MIPS: Remove unused ST_OFF from r2300_switch.S

Commit 1a3d5957 ("MIPS: Tidy up FPU context switching") removed
usage of ST_OFF, leaving it behind as dead code. Commit 828d1e4e
("MIPS: Remove dead define of ST_OFF") then removed the definition of
ST_OFF from r4k_switch.S as a cleanup. However the unused definition of
ST_OFF has been left behind in r2300_switch.S. Remove it.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16239/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/r2300_switch.S

@@ -25,12 +25,6 @@
 	.set	mips1
 	.align	5
 
-/*
- * 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)
-
 /*
  * task_struct *resume(task_struct *prev, task_struct *next,
  *		       struct thread_info *next_ti)