dt-bindings: pinctrl: k3: Introduce pinmux definitions for AM62

dt-bindings: pinctrl: k3: Introduce pinmux definitions for AM62

Add pinctrl macros for AM62x SoCs. These macro definitions are similar
to that of previous platforms, but adding new definitions to avoid any
naming confusions in the SoC dts files.

checkpatch insists the following error exists:
ERROR: Macros with complex values should be enclosed in parentheses

However, 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: Suman Anna <s-anna@ti.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>