bpf: Remove unused backtrack_state helper functions

The function are defined in the verifier.c file, but not called
elsewhere, so delete the unused function.

kernel/bpf/verifier.c:3448:20: warning: unused function 'bt_set_slot'
kernel/bpf/verifier.c:3453:20: warning: unused function 'bt_clear_slot'
kernel/bpf/verifier.c:3488:20: warning: unused function 'bt_is_slot_set'

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20231212005436.103829-1-yang.lee@linux.alibaba.com

Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=7714

kernel/bpf/verifier.c

@@ -3465,16 +3465,6 @@ static inline void bt_clear_frame_slot(struct backtrack_state *bt, u32 frame, u3
 	bt->stack_masks[frame] &= ~(1ull << slot);
 }
 
-static inline void bt_set_slot(struct backtrack_state *bt, u32 slot)
-{
-	bt_set_frame_slot(bt, bt->frame, slot);
-}
-
-static inline void bt_clear_slot(struct backtrack_state *bt, u32 slot)
-{
-	bt_clear_frame_slot(bt, bt->frame, slot);
-}
-
 static inline u32 bt_frame_reg_mask(struct backtrack_state *bt, u32 frame)
 {
 	return bt->reg_masks[frame];
@@ -3505,11 +3495,6 @@ static inline bool bt_is_frame_slot_set(struct backtrack_state *bt, u32 frame, u
 	return bt->stack_masks[frame] & (1ull << slot);
 }
 
-static inline bool bt_is_slot_set(struct backtrack_state *bt, u32 slot)
-{
-	return bt_is_frame_slot_set(bt, bt->frame, slot);
-}
-
 /* format registers bitmask, e.g., "r0,r2,r4" for 0x15 mask */
 static void fmt_reg_mask(char *buf, ssize_t buf_sz, u32 reg_mask)
 {