IB/hfi1: Keep SC_USER as the last send context type

SC_USER needs to be the last send context type to ensure other
send context types get their allocation when num_user_contexts
is set to a large number.

This fixes a panic when the module parameter num_user_contexts
is set to 141 and larger.

Reviewed-by: Dean Luick <dean.luick@intel.com>
Signed-off-by: Jianxin Xiong <jianxin.xiong@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>