arm64: defconfig: enable 48-bit virtual addresses

Some armv8 SoCs (e.g. ls2080a) have physical memory maps with discontiguous
DDR regions that require 48-bit VA to have the linear map cover the entire
range of DDR.
Signed-off-by: NStuart Yoder <stuart.yoder@nxp.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>

arch/arm64/configs/defconfig

@@ -61,6 +61,7 @@ CONFIG_PCI_XGENE=y
 CONFIG_PCI_LAYERSCAPE=y
 CONFIG_PCI_HISI=y
 CONFIG_PCIE_QCOM=y
+CONFIG_ARM64_VA_BITS_48=y
 CONFIG_SCHED_MC=y
 CONFIG_PREEMPT=y
 CONFIG_KSM=y