spi: stm32-qspi: fix pm_runtime usage_count counter

pm_runtime usage_count counter is not well managed.
pm_runtime_put_autosuspend callback drops the usage_counter but this
one has never been increased. Add pm_runtime_get_sync callback to bump up
the usage counter. It is also needed to use pm_runtime_force_suspend and
pm_runtime_force_resume APIs to handle properly the clock.

Fixes: 9d282c17

 ("spi: stm32-qspi: Add pm_runtime support")
Signed-off-by: Christophe Kerello <christophe.kerello@foss.st.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210419121541.11617-2-patrice.chotard@foss.st.com
Signed-off-by: Mark Brown <broonie@kernel.org>