wayland/weston: do not set preferred version, as v1.5.0 is built

Since there is no wayland/weston 1.4 is available from poky, do
not set un-available version which throws warning during parse:

WARNING:
NOTE: preferred version 1.4.0 of wayland not available (for item wayland)
NOTE: versions of wayland available: 1.5.0
NOTE: preferred version 1.4.0 of weston not available (for item weston)
NOTE: versions of weston available: 1.5.0

Signed-off-by: Srikanth Krishnakar <Srikanth_Krishnakar@mentor.com>