skeleton/etc/profile: drop aliases

They all depend on having a custom busybox config and/or fully featured
utilities which depend on BR2_PACKAGE_BUSYBOX_SHOW_OTHERS.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>