netifd: check if /sbin/wifi exists before calling it
Avoid harmless error from network script by checking presence of
now-optional wifi support script, most notably confusing users of x86
snapshots.
Fixes: #14964
Signed-off-by: Andris PE <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/14986
Signed-off-by: Robert Marko <[email protected]>