memory: ti-aemif: Export aemif_*_cs_timings()

memory: ti-aemif: Export aemif_*_cs_timings()

Export the aemif_set_cs_timing() and aemif_check_cs_timing() symbols so
they can be used by other drivers

Add a mutex to protect the CS configuration register from concurrent
accesses between the AEMIF and its 'children'.

Signed-off-by: Bastien Curutchet <bastien.curutchet@bootlin.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20241204094319.1050826-7-bastien.curutchet@bootlin.com
[krzysztof: wrap aemif_set_cs_timings() at 80-char]
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>