dmesg: --notime should not suppress --show-delta

dmesg: --notime should not suppress --show-delta

The --show-delta is off by default, which means it can be only on when user
has requested to see these time stamps.  The --notime option should not turn
the delta outputing off, because then option order matters and no-one wants
that.  Example of the old output:

$ dmesg --notime --show-delta | sed -n 's/ version.*//p; q'
[<    0.000000>] Linux
$ dmesg --show-delta --notime | sed -n 's/ version.*//p; q'
Linux

Addresses: https://bugs.launchpad.net/bugs/1544595
Signed-off-by: Sami Kerola <kerolasa@iki.fi>