autofs: do not check for modprobe

Reference: http://www.spinics.net/lists/autofs/msg00139.html

Loading autofs module is #ifdef'ed in the source, so
there is no need to check for /proc (which is only used
to load module) or modprobe.  Both modprobe and /proc
are always in the fixed location so there's no need to
check for these to start with.

Signed-off-by: yanjun.zhu <yanjun.zhu@windriver.com>
Signed-off-by: Joe MacDonald <joe.macdonald@windriver.com>