dt/bindings: ti,edma: Remove redundant properties from documentation

From CCCFG register of eDMA3 we can get all the needed information for the
driver about the IP:
Number of channels: NUM_DMACH
Number of regions: NUM_REGN
Number of slots (PaRAM sets): NUM_PAENTRY
Number of TC/EQ: NUM_EVQUE

The ti,edma-regions; ti,edma-slots and dma-channels in DT are
redundant since the very same information can be obtained from the HW.
The mentioned properties are deprecated.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>