It is invalid to pass in GL_TEXTURE_BUFFER to either
glTexParameter or glGetTexParameter. Return GL_INVALID_ENUM
for such usecases.

Bug: angleproject:3573
Bug: angleproject:3577
Test: dEQP.KHR_GLES31/core_texture_border_clamp_texparameteri_errors
Change-Id: Ia0573c24d38c6be9d1b79a83a05e2ffbc62c8918
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2892023
Commit-Queue: Mohan Maiya <m.maiya@samsung.com>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>