Previously, configuring the GDMA was limited to a single descriptor,
restricting memory transfers to a maximum of 4kB.
This update introduces support for multiple descriptors, enabling users
to define multiple dma_blocks. The maximum number of descriptors can be
configured via the CONFIG_DMA_ESP32_DESCRIPTOR_NUM option.
Additionally, the dma_get_status() function now reports the index of the
currently processed descriptor
through the status.read_position and status.write_position fields.
Signed-off-by: Armin Kessler <ake@espros.com>
