tests: Check for mac80211_hwsim module before loading it

Instead of checking if the kernel allows modules (via the presence of
/proc/modules), check if mac80211_hwsim is already there and load it
only if not. This gets rid of some ugly prints from modprobe in case
code isn't even a module and cannot be found, etc.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

tests/hwsim/start.sh

@@ -110,7 +110,7 @@ else
 	NUM_CH=1
 fi
 
-test -f /proc/modules && sudo modprobe mac80211_hwsim radios=7 channels=$NUM_CH support_p2p_device=0 dyndbg=+p
+test -d /sys/module/mac80211_hwsim || sudo modprobe mac80211_hwsim radios=7 channels=$NUM_CH support_p2p_device=0 dyndbg=+p
 
 sudo ifconfig hwsim0 up
 sudo $WLANTEST -i hwsim0 -n $LOGDIR/hwsim0.pcapng -c -dtN -L $LOGDIR/hwsim0 &