ARM: Clean up CONFIG_ARMV7_NONSEC/VIRT/PSCI conditions

CONFIG_ARMV7_VIRT depends on CONFIG_ARMV7_NONSEC, thus doesn't need to
be taken into account additionally. CONFIG_ARMV7_PSCI is only set on
boards that support CONFIG_ARMV7_NONSEC, and it only works on those.

CC: Tang Yuantian <Yuantian.Tang@freescale.com>
CC: York Sun <yorksun@freescale.com>
CC: Steve Rae <srae@broadcom.com>
CC: Andre Przywara <andre.przywara@linaro.org>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Tested-by: Alison Wang <alison.wang@freescale.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>