spi: hisi-kunpeng: Add debugfs support

mainline inclusion
from mainline-v5.14-rc1
commit 2b2142f2
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4UR1H
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2b2142f247ebeef74aaadc1a646261c19627fd7e



-----------------------------------------------------------------------

This patch uses debugfs_regset32 interface to create the registers dump
file. Use it instead of creating a generic debugfs file with manually
written read callback function.

With these entries, users can check all the SPI controller registers
during run time.

Signed-off-by: Jay Fang <f.fangjian@huawei.com>
Link: https://lore.kernel.org/r/1622789718-13977-1-git-send-email-f.fangjian@huawei.com


Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Jay Fang <f.fangjian@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>