regmap: kunit: Add coverage of spinlocked regmaps

regmap: kunit: Add coverage of spinlocked regmaps

By default regmap uses a mutex to protect the regmap but we also support
other kinds of locking, including spinlocks, which can have an impact
especially around allocations. Ensure that we are covering the spinlock
case by running tests configured using fast I/O, this causes the core to
use a spinlock instead of a mutex. Running every single test would be
redundant but cover most of them.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://patch.msgid.link/20240901-regmap-test-fast-io-v1-1-aad83a871bcc@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>