spi: atmel-quadspi: Update to current device naming terminology

spi: atmel-quadspi: Update to current device naming terminology

For v6.9 the spi subsystem changed the terminology to host and target
devices, see commit 99769a52464d ("spi: Update the "master/slave"
terminology in documentation") for reference.  Support for SAMA7G5 was
forward ported recently from an old vendor branch before that
terminology change, so naming for the new struct member is adapted to
follow the current scheme.

Signed-off-by: Alexander Dahl <ada@thorsis.com>
Link: https://patch.msgid.link/20250109094843.36014-1-ada@thorsis.com
Signed-off-by: Mark Brown <broonie@kernel.org>