Currently, the debugfs command for intr is implemented by
"echo xxxx > cmd", and record the information in dmesg. It's
unnecessary and heavy. To improve it, create a single file
"interrupt_info" for it, and query it by command "cat interrupt_info",
return the result to userspace, rather than record in dmesg.

The display style is below:
$cat interrupt_info
num_nic_msi: 65
num_roce_msi: 65
num_msi_used: 2
num_msi_left: 128
Signed-off-by: Jiaran Zhang <zhangjiaran@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>