spi: Fix deadlock when adding SPI controllers on SPI buses

mainline inclusion
from mainline-v5.15-rc6
commit 6098475d
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9RBZI
CVE: CVE-2021-47469

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6098475d4cb48d821bdf453c61118c56e26294f0



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Currently we have a global spi_add_lock which we take when adding new
devices so that we can check that we're not trying to reuse a chip
select that's already controlled.  This means that if the SPI device is
itself a SPI controller and triggers the instantiation of further SPI
devices we trigger a deadlock as we try to register and instantiate
those devices while in the process of doing so for the parent controller
and hence already holding the global spi_add_lock.  Since we only care
about concurrency within a single SPI bus move the lock to be per
controller, avoiding the deadlock.

This can be easily triggered in the case of spi-mux.

Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Conflicts:
	drivers/spi/spi.c
[Resolve conflicts due to several refactor patches not merged.]
Signed-off-by: Zeng Heng <zengheng4@huawei.com>