powerpc/bpf/32: BPF prog is never called with more than one arg

BPF progs are never called with more than one argument, plus the
tail call count as a second argument when needed.

So, no need to retrieve 9th and 10th argument (5th 64 bits argument)
from the stack in prologue.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/89a200fb45048601475c092c5775294dee3886de.1675245773.git.christophe.leroy@csgroup.eu

arch/powerpc/net/bpf_jit_comp32.c

@@ -159,12 +159,6 @@ void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx)
 		if (bpf_is_seen_register(ctx, i))
 			EMIT(PPC_RAW_STW(i, _R1, bpf_jit_stack_offsetof(ctx, i)));
 
-	/* If needed retrieve arguments 9 and 10, ie 5th 64 bits arg.*/
-	if (bpf_is_seen_register(ctx, bpf_to_ppc(BPF_REG_5))) {
-		EMIT(PPC_RAW_LWZ(bpf_to_ppc(BPF_REG_5) - 1, _R1, BPF_PPC_STACKFRAME(ctx)) + 8);
-		EMIT(PPC_RAW_LWZ(bpf_to_ppc(BPF_REG_5), _R1, BPF_PPC_STACKFRAME(ctx)) + 12);
-	}
-
 	/* Setup frame pointer to point to the bpf stack area */
 	if (bpf_is_seen_register(ctx, bpf_to_ppc(BPF_REG_FP))) {
 		EMIT(PPC_RAW_LI(bpf_to_ppc(BPF_REG_FP) - 1, 0));