arm64: defconfig: Enable the PMIC and regulator for Hi6220 and 96boards HiKey

This patch enables a number of devices currently supported by the Hi6220
and 96boards HiKey. These include
a) Hi655x PMIC and regulator
b) Hi6220 I2C, USB, MMC, mailbox, and reset
c) CONFIG_PINCTRL_SINGLE, and CONFIG_LEDS_GPIO

Since b) and c) are already in the 4.6-rc3, so kept a) only in this
patch and updated subject as well.

v2:
 - rebase to next-20160310, CONFIG_MMC_BLOCK_MINORS=16 is already in.
 - set CONFIG_I2C_DESIGNWARE_PLATFORM to be build as module

Signed-off-by: Guodong Xu <guodong.xu@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>