clock: Use .balign to align ticksl

[markj]

Summary

The .align directive has a different behaviour on 32-bit arm than on
other platforms. Use .balign instead, which has consistent behaviour on
all architectures.

Reported by: kib
Fixes: 6b82130e6c9a ("clock: Add a long ticks variable, ticksl")

Test Plan

Booted an armv7 kernel in qemu, checked the alignment of the ticksl symbol.