selftests/bpf: Fix the invalid operand for instruction issue

The following issue occurs when compiling with clang version 17.0.6:
progs/compute_live_registers.c:251:3: error: invalid operand for instruction
  251 |                 "r0 = 1;"
      |                 ^
<inline asm>:1:22: note: instantiated into assembly here
    1 |         r0 = 1;r2 = 2;if r1 & 0x7 goto +1;exit;r0 = r2;exit;
      |                             ^
1 error generated.

Use __imm_insn to fix this issue.

Fixes: 4a4b84b ("selftests/bpf: verify jset handling in CFG computation")
Signed-off-by: Feng Yang <yangfeng@kylinos.cn>

Author: kknjh

tools/testing/selftests/bpf/progs/compute_live_registers.c

@@ -249,11 +249,13 @@ __naked void if3_jset_bug(void)
 	asm volatile (
 		"r0 = 1;"
 		"r2 = 2;"
-		"if r1 & 0x7 goto +1;"
+		".8byte %[jset];" /* same as 'if r1 & 0x7 goto +1;' */
 		"exit;"
 		"r0 = r2;"
 		"exit;"
-		::: __clobber_all);
+		:
+		: __imm_insn(jset, BPF_JMP_IMM(BPF_JSET, BPF_REG_1, 0x7, 1))
+		: __clobber_all);
 }
 
 SEC("socket")