arm64: defconfig: Enable nvmem's rmem driver

It'll be used by the RPi4 family of boards to access its bootloader
configuration.
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Link: https://lore.kernel.org/r/20210112142342.7290-1-nsaenzjulienne@suse.de

arch/arm64/configs/defconfig

@@ -1062,6 +1062,7 @@ CONFIG_ROCKCHIP_EFUSE=y
 CONFIG_NVMEM_SUNXI_SID=y
 CONFIG_UNIPHIER_EFUSE=y
 CONFIG_MESON_EFUSE=m
+CONFIG_NVMEM_RMEM=m
 CONFIG_FPGA=y
 CONFIG_FPGA_MGR_STRATIX10_SOC=m
 CONFIG_FPGA_BRIDGE=m