sdkconfig: Switch to 16MiB partition layout

# ESP-IDF Partition Table
# Name, Type, SubType, Offset, Size, Flags
nvs,data,nvs,0x9000,24K,
phy_init,data,phy,0xf000,4K,
factory,app,factory,0x10000,6080K,
vfs,data,fat,0x600000,10M,