wifi: carl9170: Fix multiple -Warray-bounds warnings

GCC (and Clang)[1] does not like having a partially allocated object,
since it cannot reason about it for bounds checking. Instead, fully
allocate struct carl9170_cmd.

Fix the following warnings Seen under GCC 13:
drivers/net/wireless/ath/carl9170/cmd.c:125:30: warning: array subscript ‘struct carl9170_cmd[0]’ is partly outside array bounds of ‘unsigned char[4]’ [-Warray-bounds=]
drivers/net/wireless/ath/carl9170/cmd.c:126:30: warning: array subscript ‘struct carl9170_cmd[0]’ is partly outside array bounds of ‘unsigned char[4]’ [-Warray-bounds=]
drivers/net/wireless/ath/carl9170/cmd.c:125:30: warning: array subscript ‘struct carl9170_cmd[0]’ is partly outside array bounds of ‘unsigned char[20]’ [-Warray-bounds=]
drivers/net/wireless/ath/carl9170/cmd.c:126:30: warning: array subscript ‘struct carl9170_cmd[0]’ is partly outside array bounds of ‘unsigned char[20]’ [-Warray-bounds=]
drivers/net/wireless/ath/carl9170/cmd.c:161:12: warning: array subscript ‘struct carl9170_cmd[0]’ is partly outside array bounds of ‘unsigned char[20]’ [-Warray-bounds=]
drivers/net/wireless/ath/carl9170/cmd.c:162:12: warning: array subscript ‘struct carl9170_cmd[0]’ is partly outside array bounds of ‘unsigned char[20]’ [-Warray-bounds=]
drivers/net/wireless/ath/carl9170/cmd.c:163:12: warning: array subscript ‘struct carl9170_cmd[0]’ is partly outside array bounds of ‘unsigned char[20]’ [-Warray-bounds=]
drivers/net/wireless/ath/carl9170/cmd.c:164:12: warning: array subscript ‘struct carl9170_cmd[0]’ is partly outside array bounds of ‘unsigned char[20]’ [-Warray-bounds=]
drivers/net/wireless/ath/carl9170/cmd.c:125:30: warning: array subscript ‘struct carl9170_cmd[0]’ is partly outside array bounds of ‘unsigned char[8]’ [-Warray-bounds=]
drivers/net/wireless/ath/carl9170/cmd.c:126:30: warning: array subscript ‘struct carl9170_cmd[0]’ is partly outside array bounds of ‘unsigned char[8]’ [-Warray-bounds=]
drivers/net/wireless/ath/carl9170/cmd.c:220:12: warning: array subscript ‘struct carl9170_cmd[0]’ is partly outside array bounds of ‘unsigned char[8]’ [-Warray-bounds=]

Link: https://github.com/KSPP/linux/issues/268
Link: godbolt.org/z/KP97sxh3T [1]
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Acked-by: Christian Lamparter <chunkeey@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/ZBSjx236+BTiRByf@work

drivers/net/wireless/ath/carl9170/cmd.c

@@ -120,7 +120,7 @@ struct carl9170_cmd *carl9170_cmd_buf(struct ar9170 *ar,
 {
 	struct carl9170_cmd *tmp;
 
-	tmp = kzalloc(sizeof(struct carl9170_cmd_head) + len, GFP_ATOMIC);
+	tmp = kzalloc(sizeof(*tmp), GFP_ATOMIC);
 	if (tmp) {
 		tmp->hdr.cmd = cmd;
 		tmp->hdr.len = len;