Switch to unversioned Recommends and conditional
This avoid a versioned Recommends, but keeps the effects so that same
version of the mesa-va-drivers sub-package get enforced on mesa updates.
Switching to Recommends instead of Requires was due to the fact that the
package could be easily replaced.
This commit fulfill this goal in practice
Signed-off-by: Nicolas Chauvet <kwizart@gmail.com>