Some kconfig changes to reduce kernel size to avoid conflict of 0x8000
(kernel load address) + uncompressed kernel size (arch/arm/boot/Image) +
compressed kernel size (arch/arm/boot/zImage) being bigger than
0x1e00000 (tags address).
This causes mostly silent boot failures, with CONFIG_DEBUG_LL messages
such as "no ATAGS support: can't continue" or "Error: invalid dtb and
unrecognized/unsupported machine ID" can be seen on UART, though they're
not very clear that the kernel image is essentially too big for what lk
is setting up.
Manual kconfig changes:
Convert some =y to =m to reduce kernel size, mostly NFS_FS and CIFS
since those are quite big and there's no point in having them
built-in.
Disable EXT2_FS & EXT3_FS - handled by EXT4 driver
