bpf, powerpc: Fix misuse of fallthrough in bpf_jit_comp()

The user defined label following "fallthrough" is not considered by GCC
and causes build failure.

kernel-source/include/linux/compiler_attributes.h:208:41: error: attribute
'fallthrough' not preceding a case label or default label [-Werror]
 208   define fallthrough _attribute((fallthrough_))
                          ^~~~~~~~~~~~~

Fixes: df561f66 ("treewide: Use fallthrough pseudo-keyword")
Signed-off-by: He Zhe <zhe.he@windriver.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/bpf/20200928090023.38117-1-zhe.he@windriver.com

arch/powerpc/net/bpf_jit_comp.c

@@ -475,7 +475,6 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
 		case BPF_JMP | BPF_JSET | BPF_K:
 		case BPF_JMP | BPF_JSET | BPF_X:
 			true_cond = COND_NE;
-			fallthrough;
 		cond_branch:
 			/* same targets, can avoid doing the test :) */
 			if (filter[i].jt == filter[i].jf) {