main/framebuffer: refactor _mesa_get_color_read_format/type

main/framebuffer: refactor _mesa_get_color_read_format/type

Current implementation returns the value for the currently bound read
framebuffer. GetNamedFramebufferParameteriv allows to get it for any
given framebuffer. GetFramebufferParameteriv would be also interested
on that method

It was refactored by allowing to pass a given framebuffer. If NULL is
passed, it used the currently bound framebuffer.

It also adds a call to _mesa_update_state. When used only by
GetIntegerv, this one was called as part of the extra checks defined
at get_hash. But now that the method is used by more methods, and the
update is needed, it makes sense (and it is safer) just calling it on
the method itself, instead of rely on the caller.

Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>