dt-bindings: ti-serdes-mux: Deprecate header with constants

The constants to define the idle state of SERDES MUX were defined in
bindings header. They are used only in DTS and driver uses the dt property
to set the idle state making it unsuitable for bindings.
The constants are moved to header next to DTS ("arch/arm64/boot/dts/ti/")
and all the references to bindings header are removed.
So add a warning to mark this bindings header as deprecated.
Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Roger Quadros <rogerq@kernel.org>
Acked-by: Peter Rosin <peda@axentia.se>
Link: https://lore.kernel.org/r/20230721125732.122421-3-j-choudhary@ti.comSigned-off-by: Nishanth Menon <nm@ti.com>

include/dt-bindings/mux/ti-serdes.h

@@ -6,6 +6,14 @@
 #ifndef _DT_BINDINGS_MUX_TI_SERDES
 #define _DT_BINDINGS_MUX_TI_SERDES
 
+/*
+ * These bindings are deprecated, because they do not match the actual
+ * concept of bindings but rather contain pure constants values used only
+ * in DTS board files.
+ * Instead include the header in the DTS source directory.
+ */
+#warning "These bindings are deprecated. Instead, use the header in the DTS source directory."
+
 /* J721E */
 
 #define J721E_SERDES0_LANE0_QSGMII_LANE1	0x0