If an error occurs after the first kzalloc() the corresponding memory
allocation is never freed.

Add the missing kfree() in the error handling path, as already done in the
remove() function.

Fixes: 7e773594 ("sfc: Separate efx_nic memory from net_device memory")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Martin Habets <habetsm.xilinx@gmail.com>
Link: https://lore.kernel.org/r/dc114193121c52c8fa3779e49bdd99d4b41344a9.1667077009.git.christophe.jaillet@wanadoo.frSigned-off-by: Jakub Kicinski <kuba@kernel.org>