Fixed file socket leak in gst_imx_vpu_dec_decide_allocation()

Fixed leaked socket pair in gst_imx_vpu_dec_decide_allocation().  GstBufferPool *pool  was allocated twice, which stomped over the first pool so that it was never deallocted.

Also including minor bug fixes to egl_platform_fb and egl_platform_wayland to free the platform and native display when initialize fails.