mesa/main: fix inverted condition
I accidentally got one of the conditions wrong here. Sorry for the mixup.
Fixes: b112e62b ("mesa/main: do not allow MESA_ycbcr_texture enums on gles")
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I accidentally got one of the conditions wrong here. Sorry for the mixup.
Fixes: b112e62b ("mesa/main: do not allow MESA_ycbcr_texture enums on gles")