iw: change install command to make it compatible with ancient coreutils
iw: change install command to make it compatible with ancient coreutils

In older versions of the install tool from the GNU coreutils package, the -t
option is not supported.  The -t option can be safely replaced by the older
"install [OPTION]... SOURCE... DIRECTORY" format.

By changing the way we call install, we can make the iw tool more friendly to
ancient distributions.

Signed-off-by: Luciano Coelho <48024ebf6407f04843f8b4062a045f41623c6d61@nokia.com>

OSLL/iw,OSLL/iw,CTU-IIG/802.11p-iw,chunyeow/iw,TeamEOS/external_iw,greearb/iw-ct,chunyeow/iw,SoluMachines/external_iw,Distrotech/iw,CTU-IIG/802.11p-iw,idor/iw,greearb/iw-ct,Distrotech/iw,bw-oss/iw,timduru/platform-external-iw,bw-oss/iw,SoluMachines/external_iw,idor/iw,timduru/platform-external-iw,cozybit/iw,cozybit/iw,TeamEOS/external_iw