mfd: abx500: Move the AB8500 Kconfig fragment

Move the AB8500 Kconfig fragment below the AB3100 so the
menuconfig menu gets hierarchically nested and looks nice.
Having the EZX PCAP in the middle disturbs the nice
hierarchical layout from kconfig.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>