ARM: dts: am437x/am33xx: Remove hwmod entries for ECAP and EPWM nodes

Previous patches switched the ECAP and EPWM to use the new bindings.
These bindings explicitly adds the various required clocks via DT rather
than depending on hwmod.

Therefore, it is safe to remove the hwmod entries since they are no longer
needed.

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>