selftests/bpf: fix bpf_target_sparc check

bpf_helpers.h fails to compile on sparc: the code should be checking
for defined(bpf_target_sparc), but checks simply for bpf_target_sparc.

Also change #ifdef bpf_target_powerpc to #if defined() for consistency.
Signed-off-by: NIlya Leoshkevich <iii@linux.ibm.com>
Acked-by: NAndrii Nakryiko <andriin@fb.com>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

tools/testing/selftests/bpf/bpf_helpers.h

@@ -452,10 +452,10 @@ static int (*bpf_skb_adjust_room)(void *ctx, __s32 len_diff, __u32 mode,
 
 #endif
 
-#ifdef bpf_target_powerpc
+#if defined(bpf_target_powerpc)
 #define BPF_KPROBE_READ_RET_IP(ip, ctx)		({ (ip) = (ctx)->link; })
 #define BPF_KRETPROBE_READ_RET_IP		BPF_KPROBE_READ_RET_IP
-#elif bpf_target_sparc
+#elif defined(bpf_target_sparc)
 #define BPF_KPROBE_READ_RET_IP(ip, ctx)		({ (ip) = PT_REGS_RET(ctx); })
 #define BPF_KRETPROBE_READ_RET_IP		BPF_KPROBE_READ_RET_IP
 #else