wifi: mac80211: add __packed to union members of struct ieee80211_rx_status

wifi: mac80211: add __packed to union members of struct ieee80211_rx_status

The arm-linux-gnueabi-gcc compiler, align the field followed by union
members, causing size of struct ieee80211_rx_status over skb->cb
(48 bytes). By investigation, the union member starts at offset 32,
and the offset of next field rate_idx is 36 instead of expected 33, and
the total size is (unexpected) 52.

When compiling rtw88 driver, it throws:

In file included from /work/linux-src/linux-stable/include/linux/string.h:386,
                 from /work/linux-src/linux-stable/include/linux/bitmap.h:13,
                 from /work/linux-src/linux-stable/include/linux/cpumask.h:11,
                 from /work/linux-src/linux-stable/include/linux/smp.h:13,
                 from /work/linux-src/linux-stable/include/linux/lockdep.h:14,
                 from /work/linux-src/linux-stable/include/linux/mutex.h:17,
                 from /work/linux-src/linux-stable/include/linux/kernfs.h:11,
                 from /work/linux-src/linux-stable/include/linux/sysfs.h:16,
                 from /work/linux-src/linux-stable/include/linux/kobject.h:20,
                 from /work/linux-src/linux-stable/include/linux/dmi.h:6,
                 from pci.c:5:
In function 'fortify_memcpy_chk',
    inlined from 'rtw_pci_rx_napi.constprop' at pci.c:1095:4:
/work/linux-src/linux-stable/include/linux/fortify-string.h:569:25: warning: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning]
  569 |                         __write_overflow_field(p_size_field, size);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

After this patch, the size of struct ieee80211_rx_status is 48.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20260411072509.1556635-1-pkshih@realtek.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>