spi: fix return code when spi device has too many chipselects

[ Upstream commit 188f6323 ]

Don't return a positive value when there are too many chipselects.

Fixes: 4d8ff6b0 ("spi: Add multi-cs memories support in SPI core")
Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Link: https://patch.msgid.link/20250915183725.219473-2-jonas.gorski@gmail.com


Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>