spi: axi-spi-engine: omit SYNC from offload instructions

spi: axi-spi-engine: omit SYNC from offload instructions

Add optimization to omit SYNC instructions from offload messages.
Starting with IP core v1.5.0, the SYNC instruction is no longer required
for proper operation when using the offload feature. Omitting the SYNC
instruction saves a few clock cycles needed to executed which can e.g.
allow achieving higher sample rates on ADCs.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20250428-adi-main-v1-4-4b8a1b88a212@baylibre.com
Signed-off-by: Mark Brown <broonie@kernel.org>