Fix OpenGL error when generating radiance

[clayjohn]

Fixes: #40444

Looks like my hardware just silently ignored the fact that the texture was the wrong type.

Seems to work fine for me. But I was unable to reproduce the linked error.

[akien-mga]

There seems to be a second occurrence of glFramebufferTextureLayer in that file (and those are the only ones in the codebase, apart from glad code that defines it) that probably needs a similar treatment:

drivers/gles3/rasterizer_storage_gles3.cpp
2043:                   glFramebufferTextureLayer(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, sky->radiance, 0, j);
2172:                   glFramebufferTextureLayer(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, sky->radiance, 0, lod);

[clayjohn]

There seems to be a second occurrence of glFramebufferTextureLayer in that file (and those are the only ones in the codebase, apart from glad code that defines it) that probably needs a similar treatment:

The other occurence is correct. It is used when we are using a texture array for radiance. This issue resulted from copy-pasting that code.

[clayjohn]

@akien-mga Should be good to merge once CI passes.

[akien-mga]

Thanks!