arm64: defconfig: enable BLK_DEV_NVME

NVME is non-volatile storage media attached via PCIe. NVME devices
typically have much higher potential throughput than other block
devices, like SATA, NVME is a must-have requirement for ARM64 based
servers.

Signed-off-by: Timur Tabi <timur@codeaurora.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>