Keyguard: Reduce font size of clock in status keyguard (sw720dp)

When system clock is configure for a 24H clock, times like 22:22, overflows the clock
of the keyguard status view on sw720dp. This change reduces the font size of clock to
allow to fit all time formats.

Change-Id: I1416c2a0f9da039f4beb4cdb77dbc5069dc47671
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>