ARM: vexpress_defconfig: Cleanup from non-existing options

ARCH_VEXPRESS_CA9X4 is gone since commit 81cc3f86 ("ARM: vexpress:
Remove non-DT code").
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Liviu Dudau <Liviu.Dudau@arm.com>

arch/arm/configs/vexpress_defconfig

@@ -19,7 +19,6 @@ CONFIG_MODULE_UNLOAD=y
 # CONFIG_IOSCHED_DEADLINE is not set
 # CONFIG_IOSCHED_CFQ is not set
 CONFIG_ARCH_VEXPRESS=y
-CONFIG_ARCH_VEXPRESS_CA9X4=y
 CONFIG_ARCH_VEXPRESS_DCSCB=y
 CONFIG_ARCH_VEXPRESS_TC2_PM=y
 # CONFIG_SWP_EMULATE is not set