Revert "ARM: vexpress: Don't select VEXPRESS_CONFIG"

This reverts commit 848685c2.
Due to when I set 'depends on VEXPRESS_CONFOG=Y' in 'config
POWER_RESET_VEXPRESS' to get an allmodconfig build on arm64 to build,
and allmodconfig build on arm fails if this patch isn't reverted.

Link: https://lore.kernel.org/r/20200527112608.3886105-4-anders.roxell@linaro.orgSigned-off-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/mach-vexpress/Kconfig

@@ -19,6 +19,7 @@ menuconfig ARCH_VEXPRESS
 	select POWER_SUPPLY
 	select REGULATOR if MMC_ARMMMCI
 	select REGULATOR_FIXED_VOLTAGE if REGULATOR
+	select VEXPRESS_CONFIG
 	help
 	  This option enables support for systems using Cortex processor based
 	  ARM core and logic (FPGA) tiles on the Versatile Express motherboard,