staging/lustre/lnet: Fix allocation size for sv_cpt_data

staging/lustre/lnet: Fix allocation size for sv_cpt_data

This is unbreaking another of those "stealth" janitor
patches that got in and subtly broke some things.

sv_cpt_data is a pointer to pointer, so need to
dereference it twice to allocate the correct structure size.

Fixes: 9899cb68c6c2 ("Staging: lustre: rpc: Use sizeof type *pointer instead of sizeof type.")
CC: Sandhya Bankar <bankarsandhya512@gmail.com>
Cc: stable <stable@vger.kernel.org> # 4.7+
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Doug Oucharek <doug.s.oucharek@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>