mfd, TWL4030: TWL4030 need select REGMAP_I2C

Fix the build error:

  drivers/built-in.o: In function `twl_probe':
  drivers/mfd/twl-core.c:1256: undefined reference to `devm_regmap_init_i2c'
  make: *** [vmlinux] Error 1

Signed-off-by: liu chuansheng <chuansheng.liu@intel.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
[ Samuel is busy, taking it directly  - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/mfd/Kconfig

@@ -292,6 +292,7 @@ config TWL4030_CORE
 	bool "Texas Instruments TWL4030/TWL5030/TWL6030/TPS659x0 Support"
 	depends on I2C=y && GENERIC_HARDIRQS
 	select IRQ_DOMAIN
+	select REGMAP_I2C
 	help
 	  Say yes here if you have TWL4030 / TWL6030 family chip on your board.
 	  This core driver provides register access and IRQ handling