esp.c: consolidate end of command sequence after ICCS command

esp.c: consolidate end of command sequence after ICCS command

The end of command sequences for the ICCS command are currently different
between the DMA and non-DMA versions, and also different from the description
in the datasheet.

Update the sequence so that only INTR_FC is asserted in both cases, and keep
all the logic in esp_do_dma() and esp_do_nodma() rather than having some of
it within esp_run_cmd().

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Tested-by: Helge Deller <deller@gmx.de>
Tested-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20240112125420.514425-70-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>