dt-bindings: pinctrl: k3: Introduce pinmux definitions for J721E

Add pinctrl macros for J721E SoC. These macro definitions are
similar to that of AM6, but adding new definitions to avoid
any naming confusions in the soc dts files.

Acked-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Tero Kristo <t-kristo@ti.com>