Check if we are in daylight time when calculating timezone

The code that calculates the Kernel TimeZone does not check
if we are actually in daylite time prior updating the kernel
time zone. Use TimeZone.getOffset which checks for daylight
savings. Also updated setTimeZone for consistency.

Change-Id: I44565bc8df48e81370ea3bfbb099a6a5675e343d
1 file changed