arm64: defconfig: enable building the nvmem-reboot-mode module

This module is used by the Qualcomm sa8775p platform for passing the
reboot reason to the bootloader. Enable building it in the arm64
defconfig as a module.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm64/configs/defconfig

@@ -614,6 +614,7 @@ CONFIG_POWER_RESET_QCOM_PON=m
 CONFIG_POWER_RESET_XGENE=y
 CONFIG_POWER_RESET_SYSCON=y
 CONFIG_SYSCON_REBOOT_MODE=y
+CONFIG_NVMEM_REBOOT_MODE=m
 CONFIG_BATTERY_SBS=m
 CONFIG_BATTERY_BQ27XXX=y
 CONFIG_BATTERY_MAX17042=m