gfrg240_defconfig: gzip initramfs

Enable CONFIG_RD_GZIP to gzip the initramfs and significantly reduce the
size of vmlinux.bin. Previously, our system would not boot because
vmlinux.bin was too large.

U-Boot printed the following error message:

"Uncompressing Kernel Image ... LZMA: uncompress or overwrite error 1 -
must RESET board to recover"
1 file changed