dt: bindings: drm: xilinx: dp: Remove version from compatible string

Remove version from Xilinx DisplayPort compatible string. The Soft IP
is released frequently, so keeping version in compatible string isn't
scalable. The same compatible string can be used for Hard IPs as long as
the same DP driver works with correct functionality.

Signed-off-by: Hyun Kwon <hyun.kwon@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>