sysv init scripts: replace &>/dev/null redirection

"<command> &>/dev/null" is supposed to redirect all output to /dev/null.

However, in shells that don't support it (dash, ash without bash extensions),
a command like "echo a &>/dev/null" is interpreted as

(a) "echo a" in background
(b) write nothing to /dev/null (redirect <empty command> to /dev/null)

This commit replaces "&>..." with ">/dev/null 2>&1".

Signed-off-by: André Erdmann <dywi@mailerd.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>