dt-bindings: timer: via,vt8500-timer: Convert to YAML

Rewrite the textual description for the VIA/WonderMedia timer
as YAML schema.

The IP can generate up to four interrupts from four respective match
registers, so reflect that in the schema.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Alexey Charkov <alchark@gmail.com>
Link: https://lore.kernel.org/r/20250521-vt8500-timer-updates-v5-1-7e4bd11df72e@gmail.com


Signed-off-by: Rob Herring (Arm) <robh@kernel.org>