SystemUI: fix msim signal cluster text label spacing

When WiFi is on and mobile data is active with msim device, the first
mobile text label (e.g. 1) was too close to the WiFi icon. Show the
spacer as necessary.

Change-Id: I2fc4c77f448647d79d81cfa02373da477556c6b0
Signed-off-by: Roman Birg <roman@cyngn.com>