octeontx2-af: Fix memory leak of object buf

[ Upstream commit 9e0a537d ]

Currently the error return path when lfs fails to allocate is not free'ing
the memory allocated to buf. Fix this by adding the missing kfree.

Addresses-Coverity: ("Resource leak")
Fixes: f7884097

 ("octeontx2-af: Formatting debugfs entry rsrc_alloc.")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>