ARM: dts: da850: Add new ECAP and EPWM bindings

For some devices, the PWMSS is a parent of eCAP and ePWM and provides
the functional clocks for those submodules. The ti,am33xx-ecap and
ti,am33xx-ehrpwm bindings were based on this parent child relationship
where the functional clock would be grabbed from the module's parent.

However, DA850 doesn't have a PWMSS and the eCAP and ePWM provides
their functional clock themselves. Therefore, prefer the new binding
that doesn't assume this parent child relationship.

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
[nsekhar@ti.com: minor commit message fixes]
Signed-off-by: Sekhar Nori <nsekhar@ti.com>