wifi: shell: removed NULL check to net_mgmt callback

Since PR, PR_SHELL, PR_ERROR, PR_INFO, and PR_WARNING already have
an embedded `sh` NULL check, we can remove the change from PR #68809.

Signed-off-by: Pisit Sawangvonganan <pisit@ndrsolution.com>
(cherry picked from commit b6f51edd6c171996fc35c43f595c7047a3d38cf8)
1 file changed