wifi: mac80211: fix macro scoping in for_each_link_data

wifi: mac80211: fix macro scoping in for_each_link_data

The for_each_link_data() macro currently declares a local variable
__sdata directly, which could lead to compiler warnings or errors when
reused in the same function or within switch-case blocks due to variable
redefinition or invalid scoping.

To address this, restructure the macro to use an outer for-loop that runs
only once, allowing safe declaration of __sdata without polluting the outer
scope. This ensures compatibility with static analyzers.

No functional changes; this is purely a cleanup to improve macro hygiene.

Signed-off-by: Aditya Kumar Singh <aditya.kumar.singh@oss.qualcomm.com>
Signed-off-by: Maharaja Kennadyrajan <maharaja.kennadyrajan@oss.qualcomm.com>
Link: https://patch.msgid.link/20250718060837.59371-2-maharaja.kennadyrajan@oss.qualcomm.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>