arm64: looprestoration: Fix an accidental overwrite
When renumbering argument registers in 1648c232, this one register reference was missed.
The missed register was meant to compare h with 2, but accidentally ended up comparing bitdepth_max to 2. In the case of 8 bpc, there's actually no bitdepth_max parameter, so it ended up comparing an uninitialized value.
Edited by Martin Storsjö