ASoC: bcm: Standardize ASoC menu

Current Kconfig menu at [ALSA for SoC audio support] has no rules.
So, some venders are using menu style, some venders are listed each drivers
on top page, etc. It is difficult to find target vender and/or drivers
because it is very random.

Let's standardize ASoC menu

Signed-off-by: Kuninori Morimoto <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

sound/soc/bcm/Kconfig

···
 # SPDX-License-Identifier: GPL-2.0-only
+menu "Broadcom"
+
 config SND_BCM2835_SOC_I2S
 	tristate "SoC Audio support for the Broadcom BCM2835 I2S module"
 	depends on ARCH_BCM2835 || COMPILE_TEST
···
 	  DSL/PON chips (bcm63158, bcm63178)
 
 	  If you don't know what to do here, say N
+
+endmenu