spi: stm32: qspi: Fix dual flash mode sanity test in stm32_qspi_setup()

commit c2bd0791 upstream.

Misplaced parenthesis make test of mode wrong in case mode is equal to
SPI_TX_OCTAL or SPI_RX_OCTAL.

Simplify this sanity test, if one of this bit is set, property
cs-gpio must be present in DT.

Fixes: a557fca6

 ("spi: stm32_qspi: Add transfer_one_message() spi callback")
Cc: stable@vger.kernel.org
Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Link: https://msgid.link/r/20240618132951.2743935-2-patrice.chotard@foss.st.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>