regmap: Use select .. if to get IRQ_DOMAIN enabled

Ensure that we can't get randconfig breakage by doing the IRQ_DOMAIN
select automatically. Don't just do the select from REGMAP_IRQ to ensure
that the select actually gets noticed.
Reported-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

drivers/base/regmap/Kconfig

@@ -6,6 +6,7 @@ config REGMAP
 	default y if (REGMAP_I2C || REGMAP_SPI)
 	select LZO_COMPRESS
 	select LZO_DECOMPRESS
+	select IRQ_DOMAIN if REGMAP_IRQ
 	bool
 
 config REGMAP_I2C

drivers/mfd/Kconfig

@@ -376,7 +376,6 @@ config PMIC_DA9052
 
 config MFD_DA9052_SPI
 	bool "Support Dialog Semiconductor DA9052/53 PMIC variants with SPI"
-	select IRQ_DOMAIN
 	select REGMAP_SPI
 	select REGMAP_IRQ
 	select PMIC_DA9052
@@ -389,7 +388,6 @@ config MFD_DA9052_SPI
 
 config MFD_DA9052_I2C
 	bool "Support Dialog Semiconductor DA9052/53 PMIC variants with I2C"
-	select IRQ_DOMAIN
 	select REGMAP_I2C
 	select REGMAP_IRQ
 	select PMIC_DA9052
@@ -560,7 +558,6 @@ config MFD_WM8994
 	bool "Support Wolfson Microelectronics WM8994"
 	select MFD_CORE
 	select REGMAP_I2C
-	select IRQ_DOMAIN
 	select REGMAP_IRQ
 	depends on I2C=y && GENERIC_HARDIRQS
 	help