gfrg240_defconfig: LZMA compress kernel image

We would like to NOT compress our kernel image for now, but the way the
Kconfig files are written, it forces us to pick GZIP or LZMA. Since our
bootloader does not support GZIP for now, we have to use LZMA.
diff --git a/arch/arc/configs/gfrg240_defconfig b/arch/arc/configs/gfrg240_defconfig
index 5612d36..c961f71 100644
--- a/arch/arc/configs/gfrg240_defconfig
+++ b/arch/arc/configs/gfrg240_defconfig
@@ -1,4 +1,5 @@
 # CONFIG_LOCALVERSION_AUTO is not set
+CONFIG_KERNEL_LZMA=y
 CONFIG_DEFAULT_HOSTNAME="Prowl"
 # CONFIG_SWAP is not set
 CONFIG_SYSVIPC=y