Added missing validation to handle in/out
qualifier for geometry shaders

Test: KHR-GLES32.core.geometry_shader.nonarray_input.*
Bug: angleproject:5579
Change-Id: I9ee0853526ce296df1f56fb7783f9847b31e49bc
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2901256
Commit-Queue: Mohan Maiya <m.maiya@samsung.com>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>