msm: vidc: update the check to ignore extradata plane in dqbuf

userptr may or may not be a null-value. Checking for this field
to qualify a plane as extradata has no merit. Ignore that check.

Bug: 28747768
CRs-Fixed: 1037945
Change-Id: I08d85ef462f09003aaa17f6ebc5d27de7083796f
Signed-off-by: Praveen Chavan <pchavan@codeaurora.org>
Signed-off-by: Praneeth Paladugu <ppaladug@codeaurora.org>