jetson-nano-emmc.conf: update EMMC_SIZE
jetson-nano-emmc.conf: update EMMC_SIZE

to be the actual size of the eMMC, rather than the value
present in the L4T configuration file.

Signed-off-by: Matt Madison <1fa2ef4755a9226cb9a0a4840bd89b158ac71391@madison.systems>

madisongh/meta-tegra,madisongh/meta-tegra,madisongh/meta-tegra,madisongh/meta-tegra,madisongh/meta-tegra