ASoC: loongson: Fix build warning when !CONFIG_PCI

Fixes the below if kernel config disable PCI support:

sound/soc/loongson/loongson_i2s_pci.c:157:1: warning: data definition has no type or storage class
157 | module_pci_driver(loongson_i2s_driver);
| ^~~~~~~~~~~~~~~~~
sound/soc/loongson/loongson_i2s_pci.c:157:1: error: type defaults to 'int' in declaration of 'module_pci_driver' [-Wimplicit-int]
sound/soc/loongson/loongson_i2s_pci.c:157:1: error: parameter names (without types) in function declaration [-Wdeclaration-missing-parameter-type]
sound/soc/loongson/loongson_i2s_pci.c:149:26: warning: 'loongson_i2s_driver' defined but not used [-Wunused-variable]
149 | static struct pci_driver loongson_i2s_driver = {
| ^~~~~~~~~~~~~~~~~~~

Add the appropriate Kconfig dependency.

Fixes: ba4c5fad598c ("ASoC: loongson: Add I2S controller driver as platform device")
Reported-by: kernel test robot <[e-mail]>
Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]/
Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]/
Signed-off-by: Binbin Zhou <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

sound/soc/loongson/Kconfig

···
 config SND_SOC_LOONGSON_I2S_PCI
 	tristate "Loongson I2S-PCI Device Driver"
 	depends on LOONGARCH || COMPILE_TEST
+	depends on PCI
 	select REGMAP_MMIO
 	help
 	  Say Y or M if you want to add support for I2S driver for