ath11k: Wstringop-overread warning

gcc-11 with the kernel address sanitizer prints a warning for this
driver:

In function 'ath11k_peer_assoc_h_vht',
    inlined from 'ath11k_peer_assoc_prepare' at drivers/net/wireless/ath/ath11k/mac.c:1632:2:
drivers/net/wireless/ath/ath11k/mac.c:1164:13: error: 'ath11k_peer_assoc_h_vht_masked' reading 16 bytes from a region of size 4 [-Werror=stringop-overread]
 1164 |         if (ath11k_peer_assoc_h_vht_masked(vht_mcs_mask))
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/wireless/ath/ath11k/mac.c: In function 'ath11k_peer_assoc_prepare':
drivers/net/wireless/ath/ath11k/mac.c:1164:13: note: referencing argument 1 of type 'const u16 *' {aka 'const short unsigned int *'}
drivers/net/wireless/ath/ath11k/mac.c:969:1: note: in a call to function 'ath11k_peer_assoc_h_vht_masked'
  969 | ath11k_peer_assoc_h_vht_masked(const u16 vht_mcs_mask[NL80211_VHT_NSS_MAX])
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

According to analysis from gcc developers, this is a glitch in the
way gcc tracks the size of struct members. This should really get
fixed in gcc, but it's also easy to work around this instance
by changing the function prototype to no include the length of
the array.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99673


Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210322160253.4032422-5-arnd@kernel.org