ASoC: stm: 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/stm/Kconfig

···
 # SPDX-License-Identifier: GPL-2.0-only
-menu "STMicroelectronics STM32 SOC audio support"
+menu "STMicroelectronics STM32"
 
 config SND_SOC_STM32_SAI
 	tristate "STM32 SAI interface (Serial Audio Interface) support"