ASoC: rt5575: fix SPI dependency

ASoC: rt5575: fix SPI dependency

The rt5575 driver fails to link when SPI support is in a loadable
module but the codec is built-in:

x86_64-linux-ld: vmlinux.o: in function `rt5575_i2c_probe':
rt5575.c:(.text+0x9792ce): undefined reference to `rt5575_spi_get_device'
rt5575.c:(.text+0x979332): undefined reference to `rt5575_spi_fw_load'

Change the symbol in to a 'bool' and add a dependency that rules
out the broken configuration.

Fixes: 420739112e95 ("ASoC: rt5575: Add the codec driver for the ALC5575")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260202095432.1234133-1-arnd@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>