hwclock: move systz into hctosys

hwclock: move systz into hctosys

The set_system_clock_timezone() function is nearly identical to
set_system_clock(). Three additional statements are required
to include systz in hctosys.

This patch is intentionally incomplete to make reviewing the
actual required changes easier. Other patches in this set will:

 * remove set_system_clock_timezone()
 * fix messages and debugging
 * fix comments
 * and finally refactor set_system_clock()

Signed-off-by: J William Piggott <elseifthen@gmx.com>