power: smb5: set fast charge safety timer to 768 mins

Currently, fast charge safety timer expires if fast charging mode lasts
longer than 384 mins. For this length of time, battery may not get fully
charged if connected to USB/PC.

Fix it by extending fast charge safety timer to 768 mins.

CRs-Fixed: 2296089
Change-Id: I5e6f1a4ecd9b9296a0d074245024393ed11fc93c
Signed-off-by: Harry Yang <harryy@codeaurora.org>