hwclock: always set the kernel's timezone

The hwclock service should set the time zone regardless of the setting
of the clock_hctosys variable. This needs to be done to prevent issues
when the system time is being synchronized using ntp.

X-Gentoo-Bug: 434410
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=434410