Switch from make_dev_alias to make_dev_alias_p since make_dev_alias_p can
gracefully fail if the /dev/megaraid_sas_ioctl_node symlink already exists.
This can happen if mfi(4) and mrsas(4) are both attached to cards and
providing Linux emulation support. Let the first one win. An equivalent
change has been done in mfi(4). Extra credit would be to pass the
Linux emulation call to the other driver when appropriate. This will
probably be a rare case and the user can manually change where the symlink
points to.
MFC after: 3 days
2f2163ab40