ipmi: ASPEED_BT_IPMI_BMC: select REGMAP_MMIO instead of depending on it

REGMAP is a hidden (not user visible) symbol. Users cannot set it
directly thru "make *config", so drivers should select it instead of
depending on it if they need it.

Consistently using "select" or "depends on" can also help reduce
Kconfig circular dependency issues.

Therefore, change the use of "depends on REGMAP_MMIO" to
"select REGMAP_MMIO", which will also set REGMAP.

Fixes: eb994594 ("ipmi: bt-bmc: Use a regmap for register access")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrew Jeffery <andrew@aj.id.au>
Cc: Corey Minyard <minyard@acm.org>
Cc: openipmi-developer@lists.sourceforge.net
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Message-Id: <20230226053953.4681-2-rdunlap@infradead.org>
Signed-off-by: Corey Minyard <cminyard@mvista.com>

drivers/char/ipmi/Kconfig

@@ -162,7 +162,8 @@ config IPMI_KCS_BMC_SERIO
 
 config ASPEED_BT_IPMI_BMC
 	depends on ARCH_ASPEED || COMPILE_TEST
-	depends on REGMAP && REGMAP_MMIO && MFD_SYSCON
+	depends on MFD_SYSCON
+	select REGMAP_MMIO
 	tristate "BT IPMI bmc driver"
 	help
 	  Provides a driver for the BT (Block Transfer) IPMI interface