tvheadend: drop the handwritten version override

tvheadend: drop the handwritten version override

The handwritten debian/changelog is only used to override the version
reported by support/version, but it is unnecessary and causes a version
mismatch:

- Build/Prepare feeds the raw git hash into debian/changelog, so the
  binary reports ddb984f4c17f4a26fd34f3e1b24e3323f9641b75~openwrt1
  instead of the package version 2026.08.17~ddb984f4.
- The CI package test then fails because it cannot find the package
  version in the output of any installed executable.
- Without .git, debian/changelog or rpm/version, support/version falls
  back to the source directory name.
- OpenWrt already names the source directory tvheadend-$(PKG_VERSION),
  so the binary correctly reports 2026.08.17~ddb984f4 without any
  override.

Alpine uses rpm/version in the same way and does not encode its own
package release into the version either.

Signed-off-by: Josef Schlehofer <redacted>