ARC: defconfig: Cleanup from old Kconfig options

Remove old, dead Kconfig option INET_LRO. It is gone since
commit 7bbf3cae ("ipv4: Remove inet_lro library").

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>