LU-12678 o2iblnd: allocate init_qp_attr on stack.

LU-12678 o2iblnd: allocate init_qp_attr on stack.

'struct ib_qp_init_attr' is not so large that it cannot be allocated
on the stack.  It is about 100 bytes, various other function in Linux
allocate it on the stack, and the stack isn't as constrained as it
once was.

So allocate on stack instead of using kmalloc and handling errors.

Test-Parameters: trivial testlist=sanity-lnet
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: Id1f2f695f298d1883a5d6817092a6f89f1e072ef
Reviewed-on: https://review.whamcloud.com/39122
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>