dt-bindings: pinctrl: k3: Introduce pinmux definitions for AM64

Add pinctrl macros for AM64 SoC. These macro definitions are similar to
that of previous platforms, but adding new definitions to avoid any
naming confusions in the soc dts files.

Unlike what checkpatch insists, we do not need parentheses enclosing
the values for this macro as we do intend it to generate two separate
values as has been done for other similar platforms.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Tested-by: Kishon Vijay Abraham I <kishon@ti.com>
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Reviewed-by: Suman Anna <s-anna@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210226144257.5470-3-d-gerlach@ti.com