ARM: net: bpf: clarify tail_call index

As per 90caccdd8cc0 ("bpf: fix bpf_tail_call() x64 JIT"), the index used
for array lookup is defined to be 32-bit wide. Update a misleading
comment that suggests it is 64-bit wide.

Fixes: 39c13c204bb1 ("arm: eBPF JIT compiler")
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

arch/arm/net/bpf_jit_32.c

@@ -1016,7 +1016,7 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx)
 	emit_a32_mov_i(tmp[1], off, false, ctx);
 	emit(ARM_LDR_I(tmp2[1], ARM_SP, STACK_VAR(r2[1])), ctx);
 	emit(ARM_LDR_R(tmp[1], tmp2[1], tmp[1]), ctx);
-	/* index (64 bit) */
+	/* index is 32-bit for arrays */
 	emit(ARM_LDR_I(tmp2[1], ARM_SP, STACK_VAR(r3[1])), ctx);
 	/* index >= array->map.max_entries */
 	emit(ARM_CMP_R(tmp2[1], tmp[1]), ctx);