SystemUI: hide missing sim icon if hide signal option is enabled

For a cleaner statusbar, if someone is using their device without
a SIM, and they choose to enable the hide signal option, I think
it's safe to assume they would like the SIM icon hidden as well!

Change-Id: I6cba97b97dfb9a67822b54ffce008d2327a0c03b
Signed-off-by: Roman Birg <romanbirg@gmail.com>