ASoC: bcm: Use *-y instead of *-objs in Makefile

*-objs suffix is reserved rather for (user-space) host programs while
usually *-y suffix is used for kernel drivers (although *-objs works
for that purpose for now).

Let's correct the old usages of *-objs in Makefiles.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20240507155540.24815-9-tiwai@suse.deSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/bcm/Makefile

 # SPDX-License-Identifier: GPL-2.0-only
 # BCM2835 Platform Support
-snd-soc-bcm2835-i2s-objs := bcm2835-i2s.o
+snd-soc-bcm2835-i2s-y := bcm2835-i2s.o
 
 obj-$(CONFIG_SND_BCM2835_SOC_I2S) += snd-soc-bcm2835-i2s.o
 
 # CYGNUS Platform Support
-snd-soc-cygnus-objs := cygnus-pcm.o cygnus-ssp.o
+snd-soc-cygnus-y := cygnus-pcm.o cygnus-ssp.o
 
 obj-$(CONFIG_SND_SOC_CYGNUS) += snd-soc-cygnus.o
 
 # BCM63XX Platform Support
-snd-soc-63xx-objs := bcm63xx-i2s-whistler.o bcm63xx-pcm-whistler.o
+snd-soc-63xx-y := bcm63xx-i2s-whistler.o bcm63xx-pcm-whistler.o
 
 obj-$(CONFIG_SND_BCM63XX_I2S_WHISTLER) += snd-soc-63xx.o
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