bpf: Remove inline from bpf_do_trace_printk

I get the following error during compilation on my side:
kernel/trace/bpf_trace.c: In function 'bpf_do_trace_printk':
kernel/trace/bpf_trace.c:386:34: error: function 'bpf_do_trace_printk' can never be inlined because it uses variable argument lists
 static inline __printf(1, 0) int bpf_do_trace_printk(const char *fmt, ...)
                                  ^

Fixes: ac5a72ea

 ("bpf: Use dedicated bpf_trace_printk event instead of trace_printk()")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200806182612.1390883-1-sdf@google.com